I woke up on the morning of May 29, 2024 to news of a transaction I’d been hoping to see since about...oh, May 29, 2022, if not earlier.
“RHP Chen Zhong-Ao Zhuang assigned to Lansing Lugnuts from Stockton Ports”
At last.
Chen Zhong-Ao Zhuang has, until very recently, seemed to be a pretty anonymous pitcher in the A’s system. There was some initial coverage of his signing in November 2021–no doubt largely because there’s always some intrigue around Asian pitchers signing as international amateurs–and there was some positive press around how he looked in his first pro camp the following spring, but that’s about it until just about now.
There’s a reason for that, much the same reason it took so long for that transaction to happen: the Taiwanese righthander hit the injured list on June 9, 2022 and didn’t pitch in an official game again until April 10, 2024. To my knowledge–though I don’t have this 100% confirmed–that 22-month absence wasn’t the result of a major arm surgery, but rather a shoulder rehab that had a number of setbacks. I believe Zhuang did recover in time for 2023 Instructional League–he was on the roster for that, anyway–so his time between regular-season games also exaggerates the length of his time on the shelf to an extent.
In any case, the A’s have understandably been cautious with Zhuang in 2024 coming off such a long layoff, assigning him to Stockton, where he spent his two previous healthy regular-season months in 2022, and slowly getting him stretched out to 70 pitches, a mark he finally crossed in his final Ports start on May 27. To say the 23-year-old’s results have been impressive across his 32 ⅓ Low-A innings in 2024 is an understatement. Zhuang led the A’s organization in strikeout-to-walk ratio at 37/4, didn’t allow multiple runs in any of his nine tandem-start outings, and put up a 1.67 ERA in a notoriously hitter-friendly environment.
With that kind of performance, accolades begin to roll in–we’re starting to see Zhuang mentioned as a sleeper in the system. I’m here to tell you, though, that this is not an out-of-nowhere rise. Chen Zhong-Ao Zhuang has always been an excellent pitching prospect. He’s just now getting a chance to prove it.
The Pre-2024 History
Zhuang signed out of Taiwan as a 21-year-old who was said to be able to hit 95 mph as an amateur. He was also noted as throwing a curve and changeup, but as it so often is* with international amateurs, it seemed the velocity was sort of the headline attribute. Seeing as Zhuang was already 21 and hadn’t pitched professionally in Asia, there was a real lack of clarity as to where he was in terms of pitchability and how he’d fare being thrown into the professional fire stateside, but the arm strength was understandably interesting.
*I mean this about the reporting of what they bring, not really what is necessarily most impressive about the pitchers themselves. Velocity is a quantity we can grasp at in a way that feels more certain that vague notions of overall pitch quality when there’s little/no available video of the pitcher.
Zhuang impressed enough on the pitchability front in 2022 camp to generate a bit of buzz and an assignment to Stockton, where a superficial examination would’ve said he did...fine before his June injury. Zhuang pitched to a 4.71 ERA with the Ports that season across eight starts. He did show elite walk avoidance, issuing just nine free passes in 42 innings while striking out 43, but he also allowed thirteen unearned runs, bumping his RA/9 up to an unsightly 7.50. So, some good, some bad, overall reasonable work for a 21-year-old who came halfway across the world, yeah?
Having watched three of those eight starts on video, though, I was convinced that Zhuang was the best A’s pitching prospect that nobody had noticed. I had him as the 14th-best prospect in the A’s system on my midseason 2022 list. Not only did Zhuang have advanced command–evidenced by the 43/9 K/BB–but he already wielded two deadly weapons that I felt gave him more upside than all but the most-heralded pitchers in the system.
The Big Duo
You’ve always got to approach these “he topped out at X mph as an international amateur” reports with a lot of caution. Not all max velo reports are the same to begin with–there’s a difference between regularly hitting a number half a dozen times per game and hitting it once in a short outing in a showcase–and it’s never all that certain how any pitcher’s arm strength is going to adapt to a pro schedule. So, okay, Zhuang hit 95 in amateur tournament play, but what sort of velo did he actually bring to the A’s organization?
The first outing of Zhuang’s that I watched in 2022 was April 19 against Inland Empire. In the first inning of that game, he was up to 96. Right off the bat, that’s settled. Zhuang can bring the heat in a pro setting.
Now, not all “touching 96”s are created equal, though. There’s a huge difference between sitting 94-95 and touching 96 and sitting 90-94 and touching 96. Zhuang was more in the latter camp, averaging 93 mph or so overall on the pitch. That’s solid velocity, but it’s not plus velocity.
That doesn’t mean it’s not a plus fastball, though. Here are some from that Inland Empire game in 2022:
In the three starts I charted in 2022, Zhuang threw 101 four-seam fastballs. 73 went for strikes–17 called and nineteen swinging. As you can see, the pitch tends to be most impactful up in the strike zone, because it really carries. I don’t have inside knowledge on how much, unfortunately, but the carry immediately stood out visually* and was backed up by the pitch’s performance. Throw in the solid velocity and Zhuang’s clear feel for finding the zone with it, and you’ve got a strong start to base an arsenal from.
*And it’s particularly aided by the fact that Zhuang is just 6’1” and isn’t an extreme overhand guy, so the pitch has bat-missing plane through the zone with that carry.
Good as all of that is, the fastball pretty much immediately became Zhuang’s second-most-interesting pitch to me upon watching him, because he wasn’t shy about unleashing this thing:
That’s his…changeup. Or at least that’s what I call it. You’ll see it sometimes referred to as a splitter in other sources, and it might be. This season, Stockton broadcaster Tim Fitzgerald said on a broadcast that Zhuang actually throws both a changeup and a splitter (now, at least), so for all I know, the above is a mix of both–I’ve never been able to reliably* differentiate them if he does indeed throw both frequently in games. Regardless, that thing just falls off the table and fades out of sight, and it’s been in the running for best changeup/splitter in the A’s system from the moment Zhuang took the field in 2022. It might not be definitively the best one, but it’s always in consideration.
*I do give it a shot in 2024 with this knowledge, but I’ve tagged 41 as changeups and 6 as splitters, and I’m not at all confident in that tagging. In any case, that underscores that most of them look similar to each other.
So, right away, in 2022 Zhuang established himself as a guy who touched 96 with big carry, wielded a plus changeup, and commanded the strike zone despite having an unconventional background.* Somehow, nobody (publicly) seemed to notice, and the subsequent injury woes kept him shrouded in mystery, seemingly quickly forgotten among A’s pitching prospects.
*Just to be clear: I am not an expert in any way on amateur baseball, let alone international amateur baseball. I have no idea how Zhuang’s experience from age 18-21 would compare to a typical American college pitcher’s experience. So I’m not taking a shot at Taiwanese amateur baseball, or the overall Asian amateur baseball landscape, here–I really have very little idea how it all works, and there’s not all that much public info about Zhuang’s particular path. If he was at any experiential disadvantage to American 21-year-olds, it sure didn’t show, is all.
So Zhuang’s 2024 breakout in Stockton, though it’s impressive he shaved a full three runs off his ERA, is really just a continuation of that fastball/changeup/command dominance, not the beginning of it. I’ve watched five of his outings this season, and in those, the four-seamer has a strike rate of 75% and a swinging strike rate of 18.75%; the changeup has a swinging strike rate of 24.4%. He can throw either to anyone in any count and have a strong chance at a great result, especially in A-ball, and they’re clearly the bedrock of his prospectdom.
It’s everything else that’s been more of a journey.
Everything Else He Throws
In that first 2022 outing on video, Zhuang threw basically three pitches. He had the four-seamer, the changeup, and this:
As excited as I immediately was about the fastball and change, I really had reservations about this pitch. It just sort of bloops in there in the low 70s, over 20 mph below his fastball, and seems loose and easy to pick up. I didn’t get a great sample on it in 2022–34 of them–but the results didn’t hint at hidden value, as he only drew two whiffs with it and threw it for a ball nearly half the time. It looked like a 30-grade pitch; as great as the fastball/changeup combo was, I had a hard time seeing Zhuang being an effective big league starter with this curve as his primary breaking ball.
Fortunately, before he got hurt in 2022, Zhuang was already taking steps to come up with a better breaker. He still threw the curve too, but he added this short slider somewhere between April 19 and May 25 (the below is actually from the start where he left with an injury, on June 1 of that year):
It’s not a particularly tight or exciting pitch either, but Zhuang immediately commanded it better than the curve, and it clearly could get it in there with more oomph and finish than the curve, so it seemed a better starting point to work from. It was good enough to alleviate my concerns that Zhuang would never have a competent breaking ball, at least.
Still, the breaking stuff remained a question mark coming into 2024. The fastball and changeup just needed to be back to where they were and that would be great, but the rest of the arsenal ideally would show progress.
Unfortunately, Zhuang does still have more or less the same curveball as he did in 2022–big and bloopy–and I still think it’s just a 30-grade show-me offering. He’s thrown 19 of them in what I’ve tracked, only eight for strikes (one swinging). He does use it at increasingly smart junctures as a pace-changer, but it’s not going to get effective results unless he throws it a good 5 mph harder. You’d love to see him have a good vertical breaker like this to play off the carrying fastball and get a real north-south style going, but this pitch can’t carry that weight.
Where things have been more interesting is with the harder breaking ball. He started off throwing what seemed to be a higher-spin slurve, almost like a sweeper. Here's one from April 17:
Neat. Certainly a development off the 2022 incarnation. It’s not like a bigtime power breaker or anything, coming in in the low 80s, but given Zhuang’s long layoff and lack of experience throwing the pitch, there’d be reason to think he could come up with a bit more tightness and power to it as he and the pitch developed. That’s often a doable adjustment*–Joelvis Del Rosario added a ton of power to his slider midseason last year, for instance.
*Worth noting that applies to the curve too. Hogan Harris came up throwing a 20+ mph separation curve like Zhuang's (albeit on a much more convincing trajectory) but started (sometimes) throwing it harder in early 2023, for one example. So there’s theoretically a chance Zhuang could do the same with his curve and improve it.
In his very next start, on April 23, though, Zhuang unleashed this thing:
That’s a…I’m calling it a cutter?...that just…tornadoes into oblivion?
I’m not sure if that pitch is a modification of the slider or a new pitch altogether–he does still throw a few that look like those April 17 sliders, but without velocity readings (which I’ll hopefully have in more granular detail next week when Zhuang is on the Trackman-employing Dayton broadcast), it’s hard to know if this cutter has supplanted the slider (and the pitch thus has somewhat variable shape) or if he throws three different breaking pitches now.
What’s more clear is that variant that I’m calling a cutter is Zhuang’s most promising breaking ball, both in terms of visual sharpness and (extremely small-sample) results, and it may well have plus potential, particularly given how new it is. The more slurvy/sweepy variant of the breaker is fine too, and then he’s got the curve as a tertiary spinner that can just further disrupt timing given how much else hitters have to worry about fending off.
So we’re looking at a pitcher here with an imposing fastball, a plus changeup, three different breaking pitches that vary in quality but still present a whole bunch of additional looks, plus supposedly a splitter in there, and both the mechanical consistency and mound savvy to relentlessly come after hitters with all these weapons. If that sounds like Zhuang was wildly overqualified for Stockton…yeah, he was. It was getting ridiculous. In his final outing on May 27, Zhuang threw 3 ⅔ strong innings with seven strikeouts against a Modesto lineup that’s been easily the best in A-ball this season, but who he dominated in three separate outings (11 innings, 17 K, 2 BB, 2 ER). By the end of his run with the Ports, with Zhuang trying on all these different pitch shapes, it just seemed like he was toying with his opponents. Which leads me to…
The Maddux Factor
I’ve alluded to Zhuang’s pitchability and command at several points in this article, but I haven’t really said much about it beyond pointing to the walk rate, which–as I discussed at length in my last article, on Will Simpson–can be a dangerous stat to use as a proxy.
In this case, some of that pointing to the walk rate is because I don’t have that much to say about Zhuang’s command by itself. He doesn’t present as an exceptional athlete on the mound, but his delivery is simple and he seems to repeat it well. He pitches exclusively from the stretch, which helps keeps things simple, though he does have a slightly different setup over the rubber with runners on base and has had some issues overthrowing and losing his release point with runners on in a couple of outings this year. Even so, seeing as he didn’t allow multiple runs in any outing, even that hasn’t been enough to cause even a single inning to snowball on him.
I don’t know if Zhuang necessarily projects to true plus command in itself, though he should certainly be okay in that area. Part of the walk avoidance is definitely that he’s got a bulldog sort of mentality on the mound and comes right after guys with the high heat. Why wouldn’t he? The fastball/changeup combination has generally been too much for pro hitters to handle from the outset of Zhuang’s career, so nothing other than the hitter-friendly confines of Banner Island Ballpark has done anything to dissuade Zhuang from that approach. Better opposition will stress-test him more, but I see no reason to think Zhuang will suddenly walk six batters per nine innings at any point along the minor league ladder.
But there’s more to think about beyond the command. Often, we talk about “command” and “pitchability” as essentially the same thing, sort of catch-all terms for “how the pitcher’s stuff is functionally deployed.” But they really aren’t the same thing, and Zhuang provides a great illustration for the difference.
Command, in my definition–which, granted, might be a bit different* from the definitions others have–is about making your pitches go where you want them. Pitchability is broader. Command is about making each individual pitch go where you want it; pitchability is about executing the best strategy given your pitches, thus making the arsenal and that pitch-specific execution more than the sum of their parts.
Zhuang’s command, as noted above, seems pretty good. It’s his pitchability, though, that has really come to the forefront as he’s bided his time in Stockton.
I talked earlier about the different breaking pitches Zhuang throws and the different shapes and velocities they provide, and Zhuang also supposedly has the two different offspeed pitches in the changeup and splitter, however much that distinction matters. The bevy of options–and whether the cutter and slider are still functionally two different pitches or just one that he changes shape on doesn’t really matter, they’re still variants and thus options–that Zhuang now can draw from certainly gives him all sorts of opportunities to mess with timing and access any area in or out of the strike zone, and he avails himself of them with aplomb. But it’s actually with the fastball that it feels like Zhuang has increasingly toyed with hitters the most.
Zhuang has six pitches, right? Fastball, changeup, splitter, curve, slider/sweeper, cutter/slider.
Nope. He has seven.
The seventh one is something he’s had from the beginning: a two-seam fastball. It was basically his fourth pitch in April of 2022, just a little wrinkle to give hitters a bit of a different look. I didn’t think too much of it. It did seem a little more distinct from the four-seam than most two-seams do, but that’s more because Zhuang’s four-seam carries so much than the two-seam looking like any sort of money pitch. He throws maybe three four-seams for every two-seam, historically,* something like that, which reflects the four-seam’s far more impactful characteristics.
*I don’t usually trust my 4S vs. 2S tagging too much–it’s just too hard a distinction to nail with more than about 80% accuracy on most minor league camera angles (though it’s still worth doing if you’re right significantly more often than not, in my opinion, hence why I even try). Zhuang’s do differ more than average visually, but if he’s way above the zone or way gloveside with a two-seam, for instance, it’s still going to look like a four-seam, so it’s tough to be sure on every pitch. I’m pretty confident in this ballpark 3-to-1 estimate historically, though.
But what’s been particularly interesting with respect to the fastballs as 2024 has continued is how much Zhuang varies the speed across them. I realize I haven’t actually given a velocity update on where Zhuang is post-injury, so rest assured: he’s hit 97 mph in multiple games this year. His arm strength is not just intact, it’s now got an extra tick he can reach back for.
But Zhuang’s average velocity, from occasional information* on broadcasts, seems to be about where it was in 2022 still–93ish. That’s because he’ll actually vary the speed quite a bit, especially dialing down the two-seam at times. He’s had outings this year where his overall fastball velocity will range from 88-97. Jared Koenig is the only pitcher who’s been in the A’s system post-2020 that I can recall ever spanning a full 10-mph distance in an appearance like that.
*Enough pitches have been had their velocity mentioned or displayed (or his overall velocity discussed) somewhere on Stockton broadcasts I’m comfortable with this rough assessment. There will be more opportunities to quantify this precisely in Lansing.
With all the adding and subtracting from the fastball and manipulating its shape, then the otherworldly changeup, and the overall relentless walk avoidance, watching Zhuang in the Cal League really started to feel like watching prime Greg Maddux carve up the NL East. He’s even started to bust out the classic Maddux comeback gloveside two-seam:
The fact that Zhuang has continued to diversify his arsenal and search for (and execute!) all these wrinkles in the span of under 100 professional innings really speaks to his pitchability, not to mention his work ethic and intelligence in honing his craft. Time will tell what the right pitch mix and approach for him are going to be, but his development to date offers reason to think he’s got a strong chance to find them.
Questions Remaining
I’ve said several times over the past two-plus years that Zhuang is the player in the A’s system I’m highest on relative to the (indifferent) consensus; naturally, then, my evaluation doesn’t come with a ton of huge negatives. Further, Zhuang is the sort of pitcher who (especially now) is really defined by his overall complete skillset rather than some extreme pluses and potentially significant minuses.
Still, if we zoom way out, we’re talking about a pitcher who reached High-A less than three months before his 24th birthday. Zhuang has several more rungs to ascend and a lot more to prove, so let’s talk about what he needs to do to really cement his status as a potential future big league starter.
The first aspect, understandably, has to be health. That’s a huge concern for every pitcher, but even more so for one with Zhuang’s injury history and previous lost time. The good news is that he’s so polished he may not need that much more development time–I’m not sure two or three good Midwest League outings wouldn’t immediately put him at the front of the line to move up to Midland–but 1 ½ seasons is about all a pitcher can lose before there’s a real risk of his future role being impacted, to say nothing of the possibility of his skillset being affected.
The second is that like a lot of carrying fastball guys, Zhuang has been an extreme flyball pitcher his whole career. This is a big part of why his surface numbers in 2022 weren’t all that dominant–he got beaten up by the short porch at Banner Island Ballpark. Away from Stockton in 2022, batters hit .231/.258/.385 against Zhuang, whereas they hit .309/.360/.568 when he was at home. The A’s system in general has pretty homer-happy environments, especially in Las Vegas, so he’ll have to prove he can keep the ball from flying over the fence at each successive stop. He somehow kept it to just one homer in Stockton this year, an impressive achievement, and the pitchability really gives him a chance, but it’s still rightfully a question he’ll have to answer given his 2022 and overall batted-ball distribution and skillset.
The third question is what the right approach for Zhuang is. Should he be throwing seven pitches? Five? Four? Should he change speeds on the fastball this much? How much should he lean on the changeup, which he hasn’t even thrown 20% of the time this year?* How should his arsenal change to lefties and righties? How should his strategy change over three times through the order–something he really hasn’t done since 2022?
*This is counting the few I’ve tagged as splitters, too. It’s 19.75%. He’s thrown slightly more breaking pitches than offspeed pitches this year, and about 58% fastballs.
As I noted in the last section, I’m optimistic Zhuang will find good answers to this last set of questions, but “optimistic” isn’t “certain.” It’s great that Zhuang mixes everything up so much, and it seems like he’s got a lot of savvy out there, but he’s also been so advanced relative to his opponents that it’s not really a fair fight–whatever he does will look good. When it is a fair fight–whatever level that’s true at, maybe Midland–is this all this tinkering reflective of savvy or restlessness? Impressions of players like this can sometimes go from “wow, he’s outthinking everyone” to “wow, he’s really in his own head” very quickly, and it’ll be on Zhuang to adapt appropriately to on-field setbacks whenever they get in his way. All his adjustment to date has mostly been proactive, which is awesome, but it’s doesn’t necessarily prove he can adjust reactively in a productive fashion as well. He very possibly can, but we won’t know until he does.
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So all told, there’s always been a lot to like about Zhuang, he’s only adding more positives as time progresses, and his results are certainly reflecting all of his positive attributes. He’s still behind the age curve even with his promotion to Lansing, and it’s fair to say he hasn’t really been tested yet, but Zhuang has the complete skillset to move through the rest of the minors relatively quickly.
Even with his breakout this season, there still isn’t much discussion of Zhuang as one of the A’s top pitching prospects, and I think it's high time he's part of that conversation. Once you get past Luis Morales, there’s no other pitcher in the system that has as good a one-two punch of pitches and command as Zhuang does. He projects to better command than guys like Ryan Cusick and Royber Salinas, throws harder than Gunnar Hoglund, and has better tertiary stuff than J.T. Ginn. Yes, Zhuang has a troubling injury history, but (unfortunately) so do all of those pitchers–their main advantage on him is length of track record and proximity to the majors. That’s definitely reason enough that you can rank any or all of those guys above Zhuang, but you definitely don’t have to. Calling Zhuang the best non-Morales pitching prospect in the entire system is not a ludicrous idea, even*–it’d be aggressive, and I don’t think I’m quite there yet, but it’s not unreasonable.
.*When Joey Estes graduates from prospect status in a couple of weeks, it'll be a bit easier to make the case than it is today.
There’s still a lot to learn about what sort of pitcher Zhuang will end up being. In 2022, he was a novice who was seeing his first pro action; in 2024, he’s suddenly a savant relative to his opponents. Neither situation seems optimal for giving rise to a firm long-term identity, and Zhuang’s fluctuating pitch mix and wide velocity range offers all sorts of possible directions he’ll go in. The straightforward sort of projection one might give would be to say that Zhuang will be a Michael Wacha-esque mid-rotation starter; that feels like a reasonable upside for him if he stays healthy and doesn’t run into massive homer trouble. Even with homer trouble, it’s easy to imagine Zhuang having Marco Estrada’s career, and he throws harder than Estrada ever did.
That was basically how I projected Zhuang in 2022 before he spent all the time on the shelf, so it makes sense that the main thing that’s happened in 2024 is he’s continued to raise the likelihood of meeting those outcomes (certainly relative to a year ago). But the part of the conversation that his 2024 showing has also changed a bit is Zhuang’s chance to exceed a Wacha-like peak. In 2022, I didn’t see that much of an avenue for that, since Zhuang was an extreme flyball guy without impact breaking stuff; those were enough negatives to provide a seemingly clear cap on Zhuang’s big league ceiling. Now that he’s shown the ability to get the cutter/slider going and he has this gigantic arsenal, there’s some sneaky chance that Zhuang could end up being a Nestor Cortes-style outlier command/patterning/funk pitcher who can be closer to a real anchor of a rotation. Make no mistake, it’s a low chance, but the path toward that sort of outcome is beginning to emerge, and that being, say, his 97th percentile outcome rather than 99th does make a meaningful impact on how Zhuang should be thought of among the top pitching prospects in the organization.
Now that Zhuang is stretched back out and at a (somewhat) more appropriate level for his talents, the picture of who he is and what he might become should start to clarify somewhat. If he continues to dominate in the Midwest League, I won’t be the only person championing him as one of the organization’s top pitching prospects by year’s end. If he runs into some adversity or his velocity tails off somewhat as he gets deeper into a pro season than he ever has, then projecting him more toward the Estrada end of his big-league possibilities makes more sense.
Still, Zhuang’s signing and development have been a major success story so far for an A’s international scouting operation that didn’t have much go right in the decade before his acquisition. His 2024 isn’t just the beginning of him showing special abilities on the mound: it’s a logical progression from the intrigue he showed in his pro debut. It’s been great to see Zhuang healthy and effective this season, not just because he ranks as one of the A’s organization’s most promising pitchers, but also because his style of pitching is a joy to watch. The system is definitely a more fun place with him in it, and when a single player who plays every sixth day makes that sort of palpable impact on the overall viewing experience, that says a lot about the excitement he brings.