In just 64.2 innings, the Atlanta Braves fifth spot in the rotation went from a glaring red flag to spectacular strength, all thanks to a 24-year-old rookie who entered 2024 with 55 professional innings.
Although his 4.04 ERA doesn't scream dominant, Spencer Schwellenbach has quickly settled in over the last month and is even giving the NL Rookie of the Year favorite a run for his money. But what is the right-hander doing that's making it so difficult for hitters to beat him?
Braves rookie Spencer Schwellenbach is lighting up the zone
It shouldn't be shocking that a pitcher with a 3.8% walk rate is filling up the strike zone, but it's still worth highlighting (and awing over).
Among MLB pitchers with at least 60 innings pitched, only five pitchers have a lower walk rate. Of those five pitchers, only Shota Imanaga has a strikeout rate within 2 percentage points of Schwellenbach.
That's right, not only is Schwellenbach better at avoiding free passes than 97% of major league pitchers, but he's also better than 77% of MLB hurlers at getting strikeouts.
This means the Michigan native is excellent at throwing pitches in the zone. With a 47.1% zone rate, only ten pitchers throw more strikes than the Braves rookie, including AL Cy Young candidate Tarik Skubal and Minnesota Twins ace Joe Ryan.
Once again, however, Spencer holds an advantage over all ten of these pitchers in terms of stealing strikes because almost no one is better at getting chases than Schwelly.
In fact, among pitchers with at least 60 innings, only Shota Imanaga draws more chases from batters. With a 38.7% chase rate, Schwellenbach is better than Chris Sale, Paul Skenes, Tarik Skubal, Garrett Crochet, and Zack Wheeler, among 142 other pitchers at getting batters to expand the zone.
On these chase pitches, Schwellenbach has gotten 78 whiffs, 38 of his 70 strikeouts, and only allowed nine hits. The righty isn't relying on a single pitch to get these chases either. He has 56 swings out of the zone on his slider, 33 on his splitter, 24 on his cutter, 23 on his curveball, 19 on his 4-seamer, and nine on his sinker. Only his sinker has been ineffective on pitches out of the zone.
In short, the Braves rookie has been excellent at throwing pitches in the zone. When he does throw pitches out of the zone, he does an excellent job at getting hitters to swing. So... how do teams adjust?
How opponents might plan to attack Spencer Schwellenbach
You might have blinked and missed it, but since the beginning of July, Spencer Schwellenbach has turned into one of the best pitchers in baseball.
Since July 1, Schwelly has put up 0.8 fWAR and has a 2.45 ERA, both good for 20th best in baseball. He's struck out 38 batters (30.6% of batters) while only walking one. In his last three starts, he's struck out at least eight while not allowing a single free pass, which made MLB history.
Spencer Schwellenbach of the @Braves is the only MLB rookie in the modern era to strike out 8+ batters without a walk in 3 consecutive starts.
— OptaSTATS (@OptaSTATS) August 3, 2024
He's also the only rookie in the modern era with 25+ strikeouts and no walks over a 3-start span. pic.twitter.com/XS6UIe9fOJ
The righty has clearly adjusted to MLB hitting, so how do those hitters respond?
One might look at his ability to generate chases and respond by swinging less. After all, if you stop chasing bad pitchers, you put yourself in a more favorable count. But when can you do that against Schwellenbach?
Nearly half of all Schwellenbach chases happened with two strikes. One could argue that this would be the time to lay off, but only eight of these swings have come with three balls. The majority of the time Schwellenbach is getting hitters to expand the zone, he's doing so when they have to protect the plate the most and he responds by fooling hitters like Paul Goldschmidt.
The righty has faced 262 batters. 140 of those batters have seen a pitch in the zone on the first pitch. Only 24 batters have seen a pitch out of the zone and swung. While his 62.6% first-pitch strike rate is fairly average, completely laying off the first pitch will only give you a ball 53% of the time, and also cost you first-pitch swing results.
Batters have actually hit pretty poorly off Schwelly on the first pitch, only hitting .250 against him, 310th-best out of 388 pitchers. Still, this is better than how they've hit off of him overall, as the righty has limited batters to a .230 AVG against. So you either take the first pitch with 50/50 odds of it being a strike, putting yourself in a worse spot 50% of the time, or you swing, giving yourself slightly higher odds of getting a hit.
MLB hitters will adjust to Spencer Schwellenbach, but there won't be an easy solution. The 24-year-old has demonstrated excellent stuff that has batters reeling and hitting coaches scrambling for answers. Fortunately for the Braves and Schwellenbach, the answer isn't as easy to swing or not to swing.