A Phenomenon Named Matt Wisler

Earlier this year, the Tampa Bay Ray's traded for a little known Giants reliever with a 6.05 ERA in 2021. They snapped him up after the Giants opted to DFA the right-hander earlier this year. His career WAR up to now is just 0.6 with a 4.84 ERA but since joining Tampa Bay he boasts a 2.30 ERA and 34 strikeouts across 27.1 innings. Note , this is not entirely without precedent. He had posted a 1.07 ERA across 18 appearances in the shortened 2020 campaign. But this is more than just a nice comeback. A deep dive into his season reveals a fascinating tale that few in baseball are really talking about. As I prepare to go into this further I'd like to thank a friend of mine who brought up Wisler in conversation for inspiring this piece.

Peering into Matt Wisler's Baseball Savant page, he ranks low (23rd percentile) in both fastball velocity and spin rate. In plain English, the fastball is quite hittable. His average fastball is 91.5 MPH which is fairly average. To make things worse, it's also fairly straight, with only 0.8 inches average vertical movement which makes it all the more hittable. His average fastball velocity has also steadily trended down from his high of 93.9 MPH in 2015.

However, he is in the 63rd percentile in max exit velocity and has a well below league average xwOBA over his last 250 batters faced. Only 6% of balls pit in play against him were hot with the barrel of the bat. He has a an xERA of 2.86 (including his poor Giants numbers) for 2021. The hard hit rate of 26.7% is a career best including his strong 2020 campaign. Since arriving in Tampa, he enjoys a sub-1.00 WHIP and 2.17 FIP as well as a measly. 595 OPS against.

So how does he do it? He only has one secondary pitch. He's eschewed his curve and changeup from his days as a starter. He's only got the slider. But what a formidable pitch this is. Just look at these numbers. Hitters are managing a .233 average against the slider but the xBA is .193, ie: hitters are actually getting a little lucky against the slider. His slider boasts a 33.1% whiff rate and a paltry .235 xwOBA against. Is it any wonder that he turns to it 90.7% of the time with a fastball sprinkled in 9.3% of the time to keep hitters off balance as needed? That was the secret sauce in 2020 and in 2021 he had found that it's no fluke.

If you watch enough video of him you'll find that he has a remarkably simple and predictable way of putting hitters away. Versus lefties, expect a backdoor slider aimed at outside corner. Versus righties, he'll make them chase as it tails away from them or jam them inside. He has two things going for him. One is that the pitch has above league average vertical and horizontal movement. Two is that he has great command of it. He is constantly getting ahead in counts. And he's also throwing quality strikes. Most strikes thrown are finding the corners where bad contact or swinging strikes are to be found. When he is hitting the middle of the zone he is vulnerable but he's doing it rarely enough that his numbers are quite good.

The secret to his success in Tampa has been effectively becoming a one-pitch pitcher. He had begun to noticeably favor the slider in 2020 with the Twins and continued success in Tampa has hinged on continuing the trend. His success is also aided by the diverse set of arms that comprise the Rays' bullpen. From the flamethrower Pete Fairbanks to the tricky J.P. Feyereisen, the Rays send out relievers with all sorts of different profiles and mechanics. This keeps hitters off balance and uncomfortable throughout the game and has helped the Rays to an AL best 3.33 bullpen ERA. Wisler is another cog in that machine once he returns from the IL. Another unheralded find has helped the Rays on their way to another division title in baseball's toughest division in spite of their fiscal challenges.