Earlier today, Rohan wrote about how luck can change things for a hitter. But what about pitchers? Did that bloop single fall in for a hit with the bases loaded? Did that 100mph rocket get hit RIGHT at someone? We’ve all seen these examples, and furthermore, how they can skew someone’s overall numbers. Unlike hitters, pitchers want a lower wOBA, because this means they have let fewer batters get on base. Let’s talk about which pitchers have stood out based on their results (wOBA) vs. their expected results (xwOBA).
This makes complete sense to me. When Paxton has pitched, he has been better than his numbers indicate. His 4.53 ERA is pretty bad, but his FIP is 4.33, xFIP is 4.14, and SIERRA is 4.04. All of these numbers tell us that his ERA has been relatively unlucky this year, and that’s probably because he’s allowed more baserunners than he should have, based on his expected xwOBA. Make sense? Good. By the way, the league average ERA this season is 4.54, so even if you use the flawed ERA metric, Paxton has been league average at worst.
Again, this was expected. There is no question that Holder hasn’t been as good as he was last year (3.14 ERA), but he isn’t this bad (6.31 ERA). His FIP and xFIP (both 4.45) this season are more than a full run lower than his ERA, and his SIERRA is 3.75. Holder has been getting pretty unlucky based on the wOBA differential listed above, and I fully expect for him to be a serviceable, albeit maybe not as good as last year, reliever going forward.
This is an interesting one. Britton is having a decent season, but judging on his 2.26 ERA, he has been a little lucky. I don’t think he’s been *that* good, and these numbers seem to back that up. His 4.14 FIP is nearly 2 runs higher than his ERA. He does have an unprecedented 78.3% ground ball rate though, so should we be surprised that hitters can’t square him up for extra bases?
Here are some other quick hits on the rest of the team’s expected stats:
Domingo German’s wOBA allowed and xwOBA allowed are the exact same (.302), so when some Red Sox fan tells you that German is getting lucky, you can tell them to pound sand.
Tommy Kahnle’s resurgence is real and it is awesome: .252 wOBA, .246 xwOBA (top 1% of league).
Adam Ottavino‘s ERA is outperforming basically all of his peripherals, and yet his wOBA against has actually been unlucky (.279 wOBA, .268 xwOBA). This is probably because his expected slugging and expected batting average against are in the top 2% of the league. Wowzers.
CC Sabathia hasn’t been good this season, but he has been getting really unlucky as well. .363 wOBA allowed, .317 xwOBA.
Masahiro Tanaka has had an up and down season, but he has gotten hurt with some cheap home runs. His wOBA is .318, while his xwOBA sits at .311. This is probably a side effect of surrendering a .453 slugging against, while his expected slugging against is only .417.
Aroldis Chapman has still got it: .249 wOBA allowed (leads team), .262 xwOBA (top 6% of league). Either way you slice it, he’s been good.