Szymborski’s 2025 Booms and Busts: Pitchers

As someone who runs a lot of projections, I’m used to being very wrong. Of the approximately 4,000 players projected every season, some 800 or so will fail to meet their 10th-percentile projection or exceed their 90th, meaning ZiPS, and by extension Dan Szymborski, will be/look horribly wrong. There’s still time before the start of the regular season to put myself into even greater jeopardy, meaning it’s time for my annual list of favorite booms and busts. The concept for these is simple, in that these are my picks for players to change how they are currently perceived. Sometimes it’s because of a projection, sometimes because of a hunch, a gut feeling, or just something I think projections might not be capturing. Since we’re going on a limb here, there will be some epic failures, and maybe [prayer emoji] even a success or two.

As usual, let’s start with a quick review of last year’s picks, this time the pitchers.

Last season was one of my weaker years, though there were a few highlights, mainly Hunter Greene and Hunter Brown. Maybe all I need are more guys named Hunter in baseball. I said I’d eat Cincinnati chili if Nelson finished the season with an ERA above four, but he missed almost the entire year with thoracic outlet syndrome, so I’ll need a ruling from the comments whether I have to face my meaty fate or if I get a mulligan because of the injury.

OK, on to the picks, before I get sidetracked into a 700-word rant about my chili proclivities.

The Booms!

Jack Leiter, Texas Rangers

I think people are more excited about Kumar Rocker at the moment, and I think there’s a good chance that he’ll be the better pitcher in the long term, but Jack Leiter seems to me as the more likely of the two to break out first. He has more experience in the high minors than Rocker, and though Leiter still has to work out some command issues, there were things to like from his unexciting debut last season. He missed bats, even while struggling, so his strikeout rate in the majors ought to climb as he improves. Leiter walked too many batters with the Rangers last year, but he also put up a solid first-pitch-strike rate, which is a good predictive indicator of future walk rate. And call it spring optimism, but the fact that Leiter is going all-in on adopting Matt Festa’s 92-mph kick changeup gives me hope that he may have a new effective tool against lefties soon.

Spencer Schwellenbach, Atlanta Braves

Every time I watch Spencer Schwellenbach or look at his profile, I like him a little better. The ZiPS in-season projections weren’t super excited about Schwellenbach last year, as could be seen when people objected to the fairly low Atlanta win probabilities in the playoff game he was projected to start. But when the full-fat ZiPS projection, rather than the slimmer in-season model, took over, his projections improved by a significant margin. ZiPS already projects him at a 3.62 ERA for 2025, and that was before the spring. After a dominant run in the Grapefruit League, Schwellenbach’s ZiPS projection has improved by another two-tenths of a run.

Brandon Pfaadt, Arizona Diamondbacks

That’s two years in a row that Brandon Pfaadt has fallen short of his expected-performance numbers. Maybe if there’s a third time, I’ll admit defeat, but for now, I’m going assume that 2025 will be well-Pfaadt. And hey, he’s already succeeded in playoff baseball! On a more tangible note, he’s made big jumps in his first-pitch-strike rate, from a lousy 51% in Triple-A in 2022 to 64% in 2023 to 71% last year.

Zebby Matthews, Minnesota Twins

If you want to find a breakout pitcher, find someone who allows a whole lot of home runs! OK, that’s a bit of an overgeneralization, but it’s worth mentioning that when the only thing wrong with a pitcher is his bottom-line homers total, you shouldn’t let those round-trippers cloud the rest of your evaluation of him. This is why way too many people drastically underrated Corbin Burnes before he emerged as an ace; they were unable to look past the 17 homers he allowed in 49 innings for the Brewers in 2019. Zebby Matthews throws decently hard, pounds the zone for a lot of strikes, and misses bats. He deserves a quick second chance after a bad debut last year.

James McArthur, Kansas City Royals

OK, picking a pitcher who is currently out with an elbow injury to have a breakout season does not actually sound like a very good idea. James McArthur had a screw installed in his elbow this past offseason to repair a fractured olecranon, which it turns out is a part of the elbow and not a typo I made just now. McArthur was tabbed by many as a breakout pick last year, and it didn’t work out, but I think that was a good inclination. He hasn’t yet figured out how to put away batters with two strikes, but when a pitcher is good at preventing contact and not clueless about where the strike zone is located, the strikeouts tend to come sooner or later. Call that the Nathan Eovaldi rule. McArthur will certainly not allow a .347 BABIP again, and though he won’t find it easy to get saves in a Royals bullpen that is a lot deeper than it was entering last year, I think he’ll be quite good when he comes back.

Graham Ashcraft, Cincinnati Reds

Yes, I’m picking Graham Ashcraft again. YOU’RE NOT MY FATHER, YOU CANT TELL ME WHAT TO DO, AND YOU DON’T UNDERSTAND MY MUSIC!!! I’ll call it now: Ashcraft is Cincinnati’s best option for the closer role. Previously, I wanted the Reds to give him as many opportunities to start as they could, but that just hasn’t worked out. However, that doesn’t mean we should give up on him, and with a simplified game plan that lets him aggressively go after batters in one-inning stints, I think that 96-mph cutter will finally get the results that have eluded it so far. Plus, he still throws that slider that looks like a Wiffle ball pitch.

Caden Dana, Los Angeles Angels

ZiPS is not enthralled with Caden Dana in 2025, giving him a projected ERA near five for the season. At the same time, ZiPS also projects Dana as the fourth-best pitching prospect in baseball, behind Roki Sasaki, Noah Schultz, and Andrew Painter. That seems like an odd separation, so I dug deeper into the projections. I tried something different, asking ZiPS to re-project pitchers for 2026 after giving each pitcher his 70th-percentile projection in 2025. When doing that, Dana had the largest jump in long-term projection of any pitcher in baseball. I don’t usually rely on projections for this kind of thing, but given this tidbit hidden in ZiPS, combined with some top-notch scouting reports, I think I’ll put a check mark next to his name.

Ian Hamilton, New York Yankees

Ian Hamilton will start the season on the injured list due to an undisclosed illness, but that’s not keeping him off my list. He appears to have recovered from the illness itself, and the Yankees don’t seem to think he’ll be out for too long, but he needs more time to ramp up before he’s ready to pitch in major league games. As far as his boom case is concerned, Hamilton has become one of the top swing-and-miss pitchers in baseball, and even though he struggles to find the zone at times, his stuff is good enough for him to emerge as a dependable back-end reliever.

The Busts!

Jacob deGrom, Texas Rangers

Jacob deGrom is one of the best pitchers of this generation, and I’m hoping he can get another peak year or two out of his arm, because he’s just THIS close to getting my Hall of Fame vote based on his peak. I’m not so worried about his drop in velocity this spring, as it likely comes from his stated intention to dial things back a little in an effort to stay healthy. But aside from that, the fact that he hasn’t been able to pitch regularly for a long time now — he last threw 100 innings in 2019 — makes him a very real risk. I’ve seen people picking the Rangers to win the division on the back of a mostly healthy deGrom, but I just can’t get on board with expecting that. I really hope this looks dumb a year from now.

Jackson Jobe, Detroit Tigers

Jackson Jobe likely has a solid future ahead of him, one that starts fairly soon, but I’m unconvinced that he’s fully developed at this point. Yes, he had a good ERA in Double-A ball last year, but he didn’t really dominate Double-A hitters the way an MLB-ready pitcher should. He’s expected to break camp with the big league club as the fifth starter in the rotation, but I think it would be wise to have him spend a few months in Triple-A, where he made just two starts totaling nine innings last year. I appreciate the Tigers’ being aggressive with a young talent, because I think teams should challenge their top prospects, but this promotion is too soon for my liking.

Javier Assad, Chicago Cubs

I’m a believer that certain pitchers can, over long periods, pitch better than you’d expect from measures like FIP. And Javier Assad has done that so far, with a career ERA (3.40) more than a run below his FIP (4.49) in 294 career innings. However, the pitchers that do this tend to either allow a freaky high number of home runs, induce a ton of weak contact, or generate an extreme amount of groundballs. Assad doesn’t do any of these things. His ERA may very well be below his FIP — ZiPS projects the difference to be about a third of a run — but I’d submit that would be more to the credit of some of the absurdly good defensive players the Cubs have. As the saying goes, “Render unto Swanson the runs that are Swanson’s.”

Luis Castillo, Seattle Mariners

There’s no one reason for my feelings here, as there is no particular factor responsible for what we’re seeing. Rather, the decline of Luis Castillo comes down to a consistent, across-the-board erosion of his skills. His fastball lacks the explosiveness and deception it once had, and his changeup looks less baffling. The latter is one reason that lefties have crushed him over the past two seasons. The dip in his strikeout rate last year is very concerning, and I think pitching home games at T-Mobile Park is masking some of Castillo’s drop-off. As with deGrom, this one pains me; Castillo as a prospect was a big success for the ZiPS projections, which absolutely loved him more than practically anyone else did in those days, so it’s disconcerting to see him decline earlier than expected. His poor performance this spring is just another sign yet that his best days are long behind him.

Alexis Díaz, Cincinnati Reds

The drop in strikeout rate is no fluke; Alexis Díaz had one of the biggest one-year jumps in contact rate last year. You can put up with a closer who walks five guys per nine innings when he’s striking out 11, but it’s much harder to tolerate that when he’s not. As you likely know from above, I think Ashcraft could push Díaz out of the closing job fairly quickly. But I’m also not sure that Tony Santillan won’t prove himself superior as well.