25-year-old starting pitcher Spencer Schwellenbach was in the midst of a stellar follow-up to his breakout 2024 rookie season by looking like an emerging ace… until a broken bone in his pitching elbow ended the right-hander’s season in late June.
Schwellenbach was a second-round pick of the Braves in the 2021 MLB Draft. The Braves drafted him as the starting pitcher, despite Schwellenbach suiting up as a two-way player at the University of Nebraska, where he pitched just 18 games, all as the Cornhuskers’ closer, during his pre-draft college campaign.
What were the expectations?
Although he didn’t earn any votes in the 2024 National League Rookie of the Year tally, Schwellenbach’s debut season was stellar. When he was called up in late May, it took a little bit of time to settle in, but then he unleashed an incredible run in July and August before fading a bit. On the season, he posted 2.7 fWAR with an 81 ERA, 83 FIP, and 83 xFIP. Even his xERA was right in line with those other numbers, and he did it all over 21 starts and 123 2/3 innings. None of it was a coincidence, and even the pitch quality models saw him as a guy with both above-average things And above-average command, a rare combination usually reserved for top-level starters.
There was little doubt that he would be a member of the 2025 rotation. The only question is where he would technically be, since it also included Chris Sale, and two guys who were very good before returning from injury: Spencer Strider and Reynaldo Lopez. ZiPS wasn’t concerned about anything in Schwellenbach’s profile, and generally expected him to more or less repeat his 2024 success with a slight regression to the mean: 2.6 WAR in about 147 innings (compared to 2.7 fWAR in about 124 innings in 2024).
Well, the rotation became a mess pretty quickly, considering Lopez was done and Strider didn’t start consistently until late May. Schwellenbach was the team’s best starter in April, given Sale’s relatively slow start (for him), and would have also outperformed Sale in May if not for the former’s high HR/FB. By the time June ended, Schwellenbach had two more starts than Sale, over 20 more innings than the veteran, and a stunning 73/81/73 line (ERA-/FIP-/xFIP-) compared to Sale’s 60/67/78. Now, half a season doesn’t necessarily mean the top title is handed over from one teammate to another, and Schwellenbach’s HR/FB rate was quite in the way, but better xFIPing sales in half a season is still really something. At the time, Schwellenbach’s 2.4 fWAR, due to home runs, was 0.2 behind Sale’s for the team lead.
Schwellenbach’s 2025 largely picked up where his 2024 left off, as his K%-BB% was nearly identical (within 0.1 percentage points) and his FIP- dropped by 2. That said, he increased his grounder rate significantly in 2025, dropping his xFIP by 10.
2025 featured his first full career game, as well as three hilariously dominant starts and four double-digit strikeout games. It was a pretty great run, until it unceremoniously ended.
While he was on the field, what it didn’t go right? Of the 153 starters with the most innings this season, he had the second-lowest walk rate. But this didn’t affect his ability to get strikeouts, which ranked 33rd in that group. He pretty much did the job from a plate discipline perspective: hit the zone (25th), got chases (third!), got whiffs in the zone (55th), got whiffs out of the zone (22nd), and avoided contact overall (23rd).
He made this possible by throwing six pitches, each of which was used at least ten percent of the time. None of the pitches were really lit — the sextet’s worst xwOBA against was .342 on his sinker, while his slider and splitter were well under .300. Of those pitches, only the sinker and curve had shapes that were not “right”; at the same time, he showed near-precise control of his three most commonly used pitches (four-seamer, slider, splitter) as well as his cutter. There may be some debate as to whether Schwellenbach could potentially benefit from ditching his sinker and curve, as they clearly lag behind his other pitches, but given how well he pitches, it doesn’t seem necessary to do anything. drastically.
Schwellenbach’s best outing was probably his start on April 4 against the Marlins – which coincidentally gave the Braves their first win of the year after starting that disastrous seven-game losing streak. He threw eight frames with a 10/0 K/BB ratio in the Braves’ home opener – 73 of his 99 pitches went for strikes that night before Aaron Bummer wrapped things up.
That said, it was just the beginning of a handful of comically good starts for Schwellenbach this year. On May 31, he struckout 11 batters and walked none in 5 1/3 innings against the Red Sox. In what would ultimately be his last start of the year, he dominated the Phillies with a 12/1 K/BB ratio in seven frames.
That his campaign only lasted half as long as the actual season. Sure, it was just for the trajectory of the injury-plagued Braves, and especially for their rotation, but it was still bad. The timing was cruel, too, as Schwellenbach likely would have gotten an All-Star nod if he hadn’t broken his elbow.
If we have to look beyond injuries, we can point to a slightly increased HR/FB. It wasn’t as bad as, say, Bryce Elder’s or something, but it still cost him something. In particular, it was almost 20 percent against left-handed hitters, and Schwellenbach also had the unfortunate circumstance of one in three catches being hit against him with high leverage last season, ultimately putting him over the fence.
Other than that, he had few clunkers. Arguably his two worst starts of the year were against eventual World Series teams, and the game against the Dodgers was particularly low as he was chased in the fourth with a 4/1 K/BB ratio and a homer allowed to Shohei Ohtani. But in the end, Schwellenbach only had three games with an xFIP- above 102, so he was pretty much consistent in throwing decent or better.
However, the injury was downright brutal. It came pretty much out of nowhere: Schwellenbach dominated the Phillies to round out his June, said something about how sore the team felt after the outing, and shame on, the diagnostic indicated a minor fracture that ended his year. At the time, it seemed possible that maybe he could start ramping up to come back in September or something, but it was pretty clear that the Braves weren’t going to get through the loss of his talented right arm or whatever other issues they had, so there wasn’t much reason to stress out and risk rushing Schwellenbach back too soon.
If healthy, Schwellenbach should be at the top of the team’s rotation. The fact that his elbow injury was a broken bone and not a ligament problem gives hope that he can start the regular season at full strength. His late start as a full-time pitcher and his injury last season could mean Atlanta will be cautious with its innings in 2026.
Steamer has him as a noticeably above-average arm, with 3 WAR in 167 innings. That’s a top-30 projection among starters, and well-deserved considering what we’ve seen so far. ZiPS has him even better in terms of pace, but is more cautious in terms of innings total: 2.6 WAR in about 125 innings.
With Sale potentially a free agent after the 2026 season and 37 days from the start of the regular season — and uncertainty surrounding Strider’s ceiling after injury issues — it could be a pivotal year for Schwellenbach and his ability to entrench himself as one of the best pitchers in baseball and the ace of Atlanta’s starting staff.
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