AL EastAnalysis

The One-Pitch Pitcher

In September of 2020, Tampa Bay Rays manager Kevin Cash famously reminded the world what his bullpen was capable of after some animosity had risen with the New York Yankees. “And the last thing I’ll say on this is I got a whole damn stable full of guys that throw 98 mph. Period.” The relievers delivered as their league-leading 3.7 team fWAR powered the Rays to their first World Series appearance in 12 years. But in June of 2021, the Rays acquired a new arm that brought something much different to the (s)table. Despite throwing his slider over 90% of the time, right-hander Matt Wisler has found success in Tampa Bay.

Wisler’s excessive slider use has become unprecedented. It became his primary pitch in 2018, the year he left Atlanta. Ever since then, he’s used it more and more each year to the point where 90.6% of the pitches he’s thrown in 2021 have been sliders. Among the 1,542 pitches a pitcher has had at least 25 PAs end on this year, Wisler’s slider has the highest percent usage.

Of the 186 batters Wisler has faced this year, only 9 of them have seen multiple fastballs in the same at-bat, the other pitch Wisler throws every now and then. (4.8%) Needless to say, opposing batters have to be sitting on the slider every time they face Wisler. If the 2017 Houston Astros faced him, even they wouldn’t need a trash can to know what’s coming.

Since the start of 2020, Wisler has thrown 1,062 sliders, the 5th most in baseball. No other reliever has thrown more than 743, or appears in the top 22 in sliders thrown. He has put himself on another level of predictablity that isn’t seen anywhere else in baseball.

So how does one succeed at the highest level of baseball as a pitcher that only throws one pitch on a regular basis? Wisler has displayed the do’s and do not’s throughout this season. In this case, Wisler must have a slider that breaks a lot for it to be effective, and he does. Despite losing almost 1.5 inches of horizontal break from 2020, Wisler’s slider still moves 32% more than the average slider in baseball. Among the 347 pitchers who have thrown at least 25 sliders this year, Wisler’s 9.7 inches of horizontal movement ranks 67th.

Wisler has also been able to throw his slider for a strike at an efficient rate. His 248 called or swinging strikes on a slider this year ranks 4th in the major leagues. He’s also improved his walk rate from a 13.1% last year to a 5.4% this year, the 5th largest decrease in baseball. Simultainiously, his whiff rate is in the 85th percentile, his hard hit rate is in the 98th percentile and his average exit velocity against took a 6 mph dropoff after leaving the Giants.

As for what to avoid when exclusively throwing a slider, there’s a reason the Rays acquired Wisler from another contending team in June of this year. He struggled in San Fransisco during his first 21 appearances of the season.

This is that zone breakdown of every slider Matt Wisler has thrown this year. The picture on the left shows the ones he threw with the Giants, and the one of the right with the Rays. There is one glaring eyesore in the Giants chart, the overwheling number of pitches down the middle. It doesn’t take a sabermetric analyist to know it’s never ideal to throw there, and doing it 11.5% of the time is asking for trouble. Wisler was one of 36 pitchers to throw at least 250 sliders at that point in the season, and none of the other 35 were pitching in that zone any more than 10% of the time, and there Wisler was at 11.5%. As one would expect, opponents slugged .769 on Wisler’s sliders in that location.

After going to Tampa, Wisler was able to to improve on his location, and everything else has followed. The run value on his slider since joining the Rays is -5.9, after it was 4.9 with the Giants. This means that the results on Wisler’s slider has prevented nearly six runs from scoring while in Tampa after allowing nearly five runs to score in San Fran. A dramatic change between the two time periods. Wisler’s 0.9 fWAR since the start of the second half of the season leads all Major League relievers. The man with one pitch has drastically improved his slder and he’s carving up hitters who are sitting on it everytime.

Wisler is currently on the 10-Day IL with inflammation in his right-middle finger. When he’s back, he and his slider will look to contiue this run of dominance as of late and help Tampa Bay in their push for a second straight division title.

Featured image via @RaysBaseball Twitter

Daniel Curren

Daniel Curren is a senior studying communication/sports journalism at Springfield College in Massachusetts. He is a rare but proud Red Sox fan from New York and has a passion for all things sabermetrics. He also co-hosts Above Replacement Radio on Apple Podcasts, Spotify, and YouTube.

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