Tommy Kahnle’s outing on Sunday was ugly — no doubt about that. Four runs on two homers in just a single inning is definitely an ERA killer, but guys have bad outings every now and again. Kahnle’s body of work this season suggests his performance on Sunday was the exception, not the rule. He’s shown to be a completely different pitcher this season, miles better than last season, and even better than his 2017.
Health has brought the return of his fastball velocity, which has definitely helped him regain some of the effectiveness last season, but the real driver of his success in 2019 has been his changeup.
Kahnle’s go-to offspeed pitch has always been his changeup. According to FanGraphs’ pitch value statistics, it’s been better this year than at any other point in his career, and some Statcast data shows hitters aren’t touching the offering. Kahnle has a 54.2 whiff percentage, and 25 of his 35 strikeouts this season have come off changeups.
When hitters do make contact with it, the ball doesn’t go anywhere either. Hitters have a measly 83.3 MPH average exit velocity and an average launch angle of 0 degrees. These two statistics help account for Kahnle’s great batted ball profile on changeups. Opponents own just a .111 batting average and .178 slugging percentage against the pitch. Overall, no Yankee reliever has allowed less hard contact than Kahnle, and the changeup has a lot to do with that.
The success with the pitch is certainly a great thing to see after such a terrible year last year, but oddly enough, those statistics aren’t all that different from his 2017 campaign with New York.
What has changed is how he uses the pitch off his fastball, and that’s led to his 2019 success. In terms of usage, Kahnle throws a lot more changeups than in he did in 2017. Back then, he threw a change 21.8% of the time and fastballs 63.4% of the time. He’s since nearly doubled his changeup usage at the expense of his fastball. Changeups account for 41.3% of his pitches in 2019 and fastballs just 53.6%. More change pieces have made at-bats against Kahnle a guessing game, and hitters are wrong more often than not.
Speaking of guessing games, Kahnle does well to tunnel his pitches, keeping fastballs and changeups on similar trajectories until the hitter has to start his swing. Here’s an example GIF:
Tommy Kahnle, 96mph Fastball (foul) and 89mph Changeup (Swingining K), Overlay/Tails. pic.twitter.com/AOUktiosO1— Rob Friedman (@PitchingNinja) April 23, 2019
Both his fastball and changeup stay on the same plane until the hitter has to begin swinging. Here’s a screenshot of that moment. It’s almost unfair:
This particular sequence doesn’t show it, but Kahnle’s also doing a decent job of locating those two pitches a bit better than previously. Here’s his heatmap from the 2017 showing the location of his fastballs and changeups:
Lots of pitches middle-middle. Compare that with his 2019 heatmap of the same pitches:
He’s still in the middle of the plate, but he’s a lot closer to the lower half of the zone than he was two years ago. It’s a small difference in location to be sure, but that part of the strikeout zone is safer than where he was in 2017.
Sure, Kahnle looked awful on Sunday. That makes this piece seem weirdly timed (because I wrote it Saturday), but his entire body of work this season suggests his outing against Cleveland was just a clunker. Perhaps only throwing once this past week had something to do with that.
Regardless, Kahnle is throwing more changeups in 2019, and he’s on track to make it a career year. No doubt his healthy shoulder and regained fastball velocity plays a part in all this as well, but without a legitimate secondary offering, pitchers will often struggle. Just ask Chad Green. Thanks to his changeup, Kahnle is thriving once again.