Matt Wisler Only Throws One Pitch. Does That Strategy Work?

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A couple of weeks ago, I was watching my hometown Toronto Blue Jays take on the Kansas City Royals in MLB's YouTube game of the week, as one does on a lazy Wednesday afternoon. They posted a graphic during the broadcast while Royals closer Scott Barlow was pitching, showing the pitchers who use their fastball the least out of everyone in baseball, and Barlow himself was among the bottom-5 in MLB.

The one who used their fastball least of all was Tampa Bay Rays reliever Matt Wisler, and it wasn't particularly close. It still isn't. I hadn't yet posted an article for FanSided at the time, so I was still familiarizing myself with the Rays and looking for ideas to write about. The Matt Wisler graphic sent me down a rabbit hole of gigantic proportions.

He only throws one pitch. He isn't a knuckleballer. Most importantly, he's an established part of a big-league bullpen. The question has to be asked: Is this a viable strategy? Could anybody else do it?

As of June 28, Wisler throws a slider almost exclusively, 92% of the time. He throws a four-seam fastball the remaining 8%, a weapon he mostly uses against right-handed hitters, targeting them down and on the outer half of the strike zone. The fact that he throws one pitch virtually all the time is nearly unprecedented for someone who doesn't throw the rarely-seen knuckleball.

Of course, there are a whole bunch of pitchers who do not rely on a four-seam fastball; Corbin Burnes, Clay Holmes, and Josh Hader are high-end examples, but all of them rely on some other sort of fastball, whether it be a sinker, cutter, or splitter. Wisler is the only one in the group that doesn't rely on any. His slider is all he uses to get by. For almost every at-bat against him, the slider is the only pitch the opposing hitter will see.

It is a very Rays-like trait for a pitcher to only throw a single off-speed pitch over 90% of the time, but Wisler became a one-trick pony a few years before coming to St. Pete. He emerged as a starter for the rebuilding Braves in the mid-2010s but was never able to establish himself as someone that opposing hitters should take seriously.

This all culminated in a disastrous 2017 season, where Wisler was moved to the bullpen with the hope that he would be more effective. Instead, he posted an 8.35 ERA, 5.20 FIP, and surrendered a .971 OPS by the opposition in 32.1 innings. Hitters were batting nearly .400 against his sinker, which simply did not play at the big-league level. He was completely lost in every sense of the word.

The Braves kept him around in 2018, but Wisler did not improve by much, and they were in a contending spot at the trade deadline, so they shipped him off to a retooling Reds team in a trade that sent serviceable outfielder Adam Duvall the other way.

With Cincinnati, Wisler showed glimpses of hope for the first time in years: in an albeit small sample size of 13.2 innings, his ERA and FIP plummeted to 2.03 and 3.91 respectively. However, this was still deemed not good enough as the Reds loaded up in the winter for another run at contention, which ultimately failed. They designated him for assignment and traded him to the Padres, the team that drafted him, just before opening day.

It was that 2018 season when Wisler made the slider his primary pitch. He still threw multiple other ones at the time, but that brief stint in Cincinnati uncovered the fact that he had a promising weapon in his arsenal. He stuck with it in 2019, and it became an objectively elite pitch, but his overall struggles continued because his sinker was still getting clobbered despite him throwing it less. With no sustained success in a relief role in San Diego, or in Seattle while flip-flopping between the rotation and bullpen in the second half of that year, Wisler was still left searching for that spark of magic he had with the Reds. Enter: the first-class pitching development of the Minnesota Twins.

They claimed him off waivers before the shortened 2020 season, and under the tutelage of now-former Twins pitching coach Wes Johnson, Wisler dropped the sinker entirely and promptly became one of the best relief pitchers in all of baseball. Averaging over an inning per appearance and occasionally being used as an opener, he put up a scorching 1.07 ERA, 2.71 Statcast xERA, 3.35 FIP, the highest strikeout rates of his career, and the lowest home run rates of his career. Despite all of that, it was 2020, and every breakout performance had to be taken with a bigger grain of salt than otherwise. The Twins ultimately didn't buy it in the long run, and he was left non-tendered.

He started 2021 with the Giants, and his ERA ballooned back up to over 6. He kept the same pitch repertoire he did in 2020, which he still has today, but his slider underperformed, and the Giants flipped him to the Rays less than halfway through the season. In doing so, they broke a cardinal rule of trading in Major League Baseball. You do not trade reclamation project pitchers with exploitable strengths to the Tampa Bay Rays. Wisler made this loud and clear once he arrived on the gulf coast. With the help of the Rays' pitching coaches, he brought the life back to his slider, and in just under 30 innings after the trade, he put up a 2.15 ERA and 2.22 FIP and has been an effective relief pitcher ever since.

Wisler has had a tumultuous career, and the lengths he has had to go to in order to become a successful major leaguer are interesting and almost completely unforeseen. So far in 2022, his 2.08 ERA is backed by impressive peripheral numbers, including a .208 expected batting average and a 30% hard-hit rate against. That well-documented slider sits at an average of 80 mph, slower than league average, and hitters are batting .189 against it so far. He exclusively throws it in the lower half of the strike zone, on both sides of the plate. It's the calling card of a very important piece of the Rays' bullpen, given all the injuries their relievers have sustained as of late. Wisler is going to continue to be tasked with pitching in high-leverage spots, and since his success hinges almost entirely on that one pitch, let's dive into the pros and cons of an unorthodox repertoire such as this one.

The biggest downside to being a one-pitch pitcher, as Wisler is actively demonstrating, is certainly his predictability. He has been below-average in both strikeout and walk rates this year, which makes intuitive sense: when batters only have one pitch to time up, it becomes easier to make contact with it and lay off it once they've seen it a few times. Some pitchers make a living off of guesswork: Shohei Ohtani, for example, becomes nearly unbeatable when he gets ahead in the count because he has a blazing 97-mph fastball, a slider with devastating bite, and a splitter with 32 inches of drop. When a hitter is down 0-2 to a pitcher like that, it's anyone's guess as to what they'll see next. With Wisler, there isn't any of that. Hitters can sell out to his slider and be correct 9 times out of 10. The only question is whether they can do anything with the contact they make.

The good news is that predictability can easily be offset if the pitch is good enough. By one measure, Wisler's slider is better than over 90% of sliders in MLB. Statcast estimates that his slider has saved the Rays an estimated 5 runs against, which ranks 37th out of the 401 different MLB pitchers that use that pitch. What's curious is that it isn't the kind of slider that seems unhittable based purely on its break. It has just a little more vertical drop (+2%) and less horizontal movement compared to average, according to Statcast. The location is what makes it so potent.

His 2022 heatmaps show that he always paints it right on the corner, down, and in to both left-handed and right-handed batters. As a right-handed batter, it's difficult to time that pitch up because a slider that ends up down and in appears as though it will hit them square in the hamstring coming out of the pitcher's hand. As a lefty, it appears to be going way outside before a dramatic sweep across the strike zone crosses them up. The uniqueness of this pitch lies in the uncanny command that Wisler has of the zone.

Things didn't click with the Giants, but ever since Wisler became an almost-exclusive one-pitch pitcher, he has been dominant with both the Twins and Rays. His 2.74 ERA since the start of 2020 ranks top-15 among all relief pitchers with at least 90 innings pitched. He came up as a highly-touted starter, mostly because of how many pitches he threw, and even though it took him years to do so, he reinvented himself in the bullpen and has essentially dropped 3 of the 4 pitches he used in his rookie season when he was still a starter. The story of how he got to become such an effective pitcher is one of the most interesting that can be found in baseball today.

Now, for the verdict: could anyone else potentially follow in his footsteps and become a valuable pitcher with just one weapon in their repertoire? I think the answer is yes, but with numerous asterisks; the first being that it would never work with a fastball unless it averages over 100 mph in velocity like Aroldis Chapman's did during his prime. As well, if the question were to come up as it did for Wisler, who failed as a 4-pitch starter, I would only trust a very small number of organizations to actually pull the trigger and make that decision. The Twins have had one of the best pitching development staffs in baseball for years. Joe Ryan, Devin Smeltzer, and Jhoan Duran are just 3 of the numerous young arms that have found success once they've landed in that organization. Tampa Bay is of similar status, and they also have a top-tier training staff, which is very important considering the long-term health implications of throwing only sliders on a pitcher's elbow.

Any organization can simply tell a failed starter to become a reliever and only throw his best pitch, but only a few have the track record to suggest that they could successfully carry that process out. The Rays and Twins are two of them. The Astros also deserve a shoutout for their unmatched list of homegrown pitchers, as do the Cleveland Guardians to a slightly lesser degree. Other Matt Wisler's could emerge in the future, but it can't be done by just anyone. There are so many repercussions that come along with a process like this, whether it's the practice of increasing speed, spin, or developing pinpoint command as Wisler himself did.

Nevertheless, it is easy to appreciate not only what he means to the Rays bullpen but the story of Wisler's entire career. He has become one of the best relievers in baseball in what might be the strangest way possible, but it's working for him and it has for some time now, and with the right circumstances, other pitchers could take after him in the coming years. To even be a one-pitch pitcher without overpowering velocity in 2022 defies all logic of how the art of pitching has been taught in recent years, but Matt Wisler is somebody that should be celebrated for it.