Aaron Bummer has had a better season than just the surface numbers might say.
A 4.50 ERA is never going to jump off the page at you. It’s pretty average production for a pitcher and in some circles, considered below average. That’s Aaron Bummer’s ERA through the first 5 weeks of the season, and so it’s easy to conclude Aaron Bummer has been an average relief pitchers so far 2024. Or even below average.
I don’t think either has been the case. Has he been elite, no. But I think he’s been better than the general fanbase thinks.
The easiest way to show this is to point out that 4.50 ERA is accompanied by a 2.81 FIP, a 2.31 xFIP, a K/9 of almost 10 and a BB/9 of 2. Those are all fantastic peripherals, and all point to the conclusion that Bummer is experiencing a common occurrence where results early in a baseball season don’t align with the process that’s went into them, leading to some unfortunate mischaracterizations. See “AJ Minter, April 2023” for further reading into the subject.
And it’s not hard to see where some wonky stuff has been happening. Bummer has induced a 60% ground-ball rate so far in 2024, an elite number and one that should lead to favorable results for any pitcher. For the season, the league-wide batting average on grounders is .239. Not at all surprising, hitting the ball on the ground is a tough way to make a living for any offensive player. But when Bummer has induced a ground-ball this season, the batting average against him is .409. The league-wide wOBA for grounders this season is .223. The wOBA against Aaron Bummer grounders so far this season is .366. Those are massive gaps and there’s no chance that’s going to last. The league is not going to continue to have elite levels of production on ground balls against Bummer while the league-wide numbers are so putrid. This is small sample size theatre at its finest.
It should be pointed out, Bummer hasn’t been completely blameless in this. The average exit velocity on his grounders this season is 91.1 mph, a very high number and 6 mph above the league average number for ground balls. But even 91 mph ground-balls shouldn’t be producing a .409 batting average and a .366 wOBA. He’s had a few that, yes were hit hard, but hit straight down into the ground and with better luck, should’ve been outs.
This ball was hit 103 mph but you wouldn’t know it because it was hit at -20 degrees launch angle and just so happened to be hit where no one was standing:
Exact same thing here, this ball was hit 98 mph but at -18 degree launch angle. Straight into the dirt and straight to where no one was standing:
This one from the other night was hit hard again, but right at the bag where Ozzie Albies was standing for an inning-ending double play, except on the way by it hit Bummer in the leg and everyone was safe. As Brandon said, bad luck.
Bummer has also been the victim of bad timing. He’s only given up 6 runs all year but 3 of those came in his first two outings of the year against Philadelphia. And those first two outings were his first ever in a Braves uniform and therefore the first impressions he made to Braves’ fans. And first impressions can be hard to shake. Since then, Bummer has been tremendous with a 2.70 ERA, a 3.04 FIP, a 2.45 xFIP, striking out 10 and only walking 2 in 11 appearances.
And the stuff his throwing has been electric. Nasty, even.
Look at this sweeper:
Aaron Bummer, Bohemian Rhapsody Sweeper. ☠️⚰️ pic.twitter.com/f9Rt41gi1L
— Rob Friedman (@PitchingNinja) April 22, 2024
And this one:
Aaron Bummer, 2 Time Zone 84mph Sweeper. ⏲️ pic.twitter.com/gIzhLoECXx
— Rob Friedman (@PitchingNinja) April 28, 2024
Once some of this BABIP variance settles down, better surface level numbers should follow. Left-handed hitters aren’t going to run a .556 BABIP all season against him like they have the first 5 weeks as more and more of those grounders are going to find gloves. And my guess is those exit velocity problems are also a product of small sample size theatre and by the end of year, he’ll be down closer to the 88-89 mph range that he’s averaged for his career vs the 91 mph his averaging at the moment. And as that drops, most of his expected numbers will look substantially better as well.
The caveat to all this is, of course, Bummer is a reliever and anything can happen with relievers. Anything. It’s the highest variance position group in baseball and there’s not a close second. They’re impossible to predict. But if Bummer continues to run the same profile he’s run to this point, a 60% ground-ball rate and a 4:1 strikeout to walk ratio, I like his chances of being a tremendous reliever for the Braves in 2024.