Just 33 starts into his big league career, Spencer Schwellenbach has proven he has all the offerings to be a quality major leaguer for quite some time for the Atlanta Braves. He came out the gates hot to begin 2025, but after a few rough starts against Toronto and the Dodgers, Schwelly has gotten right back on track with the notable exception of his breaking stuff.
His last two outings have been historic in the sense that he became the first pitcher to register 11 strikeouts and issue no walks in consecutive starts since Zac Gallen did so in April of 2023. In what has been a rollercoaster ride for the Braves the last two seasons, Schwellenbach has been one of the few constants. However, the Braves could get more from their 2021 second round pick if they focus on improving one part of his arsenal.
Spencer Schwellenbach's 9th and 10th Ks thru 6. pic.twitter.com/XbzkZ8pRFQ
— Rob Friedman (@PitchingNinja) May 31, 2025
Braves fixing Schwellenbach's slider could turn him into a Cy Young candidate
Schwellenbach is a very unique pitcher because he throws six different pitches that carry at least a 9% usage. His four-seam fastball leads the way of course, averaging 97 mph and striking out 23 batters so far in 2025.
Not to be outdone, his splitter has become a very effective weapon against left-handed hitters. Schwellenbach's splitter carries a 36.4% whiff rate and is limiting hitters to a .163 slugging percentage. The problem this year (if you are nitpicking for problems) is the inconsistency with his breaking pitches.
Outside of the four-seam fastball, Schwellenbach throws his slider the most compared to any of his other offerings at 19%. Against right-handed batters that pitch has been mostly fine, but Schwellenbach has hung a few too many sliders against powerful lefties in the no-no zone down and in this season.
Last year, Schwellenbach generated about an inch more horizontal break on his slider. The same can be said for his less often used curveball. As things stand, Schwellenbach's slider (-3 run value) and curveball (-1 run value) are the only pitches that carry a negative run value according to Baseball Savant. This could balance out as the season goes along, but it's clear Schwelly's not getting the same finish on his breaking pitches as he did before.
The solution is likely a small mechanical adjustment and before we know it, Schwellenbach could have a more consistent and devastating breaking ball to pair with his now 100 mph fastball. Not much has gone right for the Braves in 2025, but Schwellenbach's continued promising development is one silver lining this season. Should Schwellenbach tinker with his breaking pitches in an effective way over the rest of the year then the rest of baseball could be in a world of trouble.