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Chasing Andrew Kittredge

The Rays reliever has become one of the best in baseball in one specific category.

MLB: Tampa Bay Rays at Baltimore Orioles Mitch Stringer-USA TODAY Sports

Andrew Kittredge has been one of the most reliable relievers in the Rays bullpen so far this season. Currently, he leads all Rays relievers (not including bulk pitchers like Josh Fleming or hybrid pitchers like Michael Wacha) with 41.0 innings pitched and a microscopic 1.54 earned run average.

With the many injuries that have plagued the Rays bullpen (and pitching staff in general), Kittredge has been one of the few constants — a surprising turn of events as the reliever recently rehabilitated an elbow tear — forcing himself into the A-bullpen with Diego Castillo, Pete Fairbanks and newcomer J.P. Feyereisen.

It’s hard to believe that, as recently as 2018, Kittredge pitched to a 7.75 ERA as a 28 year old rookie. But quite a bit has changed since then. The results may not show it right away, but his transformation started in 2019. While pitchers were throwing less sinkers and throwing more four seamers, Kittredge did the exact opposite, not only adding a sinker, but making it his primary fastball.

Clearly, it was something that Kittredge worked on that offseason, because he came out of the gate throwing it almost 40 percent of the time when he started pitching for the major league ball club in June.

Why, in an era where rising four seam fastballs are all the rage, would Kittredge dare to zig while everyone else zags? Further, how has he found such great success while others have tried to adopt the sinker and failed?

Creating a tunnel

The answer lies in Kittredge’s ability to create a tunnel with his pitches. While some pitchers on the Rays such as Tyler Glasnow and the aforementioned Feyereisen use a tunnel as a means of working north and south thanks to some of the best vertical movement in the game, Kittredge has mastered the ability to use the tunnel to work east to west with the sinker and slider thanks to great horizontal movement on both pitches.

According to Texas Leaguers, Kittredge gets -9.70 inches of horizontal movement on his sinker (meaning armside movement) and 4.02 inches of horizontal movement (glove side movement) on the slider. Relative to the league average, the sinker moves an extra inch, while the slider moves an extra 4.2 inches. For some context, Kittredge’s slider has more than twice as much horizontal movement than the average slider thrown at a similar velocity and release point.

By run value per 100 pitches on Baseball Savant, Kittredge’s sinker and slider both rate well above average. Of pitchers who have faces at least 50 hitters, his sinker rates 10th best in all of baseball, while his slider rates fifth best. In practice, we can see exactly how Kittredge can use these tools to deceive hitters, like he did during this at bat against Cleveland outfielder Oscar Mercado, first with the sinker inside, then with the slider down, then with both pitches overlayed.

This brings us to another piece of what has turned Kittredge into an above average bullpen arm. From the GIF above, we can notice at least three consistencies: The pitch tunnel, the batter Mercado whiffing at both pitches, and the revealing detail that both pitches were outside the zone.

In 2019, Kittredge was the best pitcher in baseball in terms of getting hitters to swing at pitches outside the zone. This metric “regressed” in 2020, mostly due to the fact that he only threw 8.0 innings due to injury. But in 2021, he is back at it, possessing the best chase rate among MLB pitchers who are not two time Cy Young Award winner Jacob deGrom.


Rays reliver Andrew Kittredge has blossomed into not only one of the best relief pitchers on the Rays, but one of the better relievers in baseball. But it didn’t happen overnight—it took a change in repertoire and a change in philosophy to make it happen.

Now, Kittredge is more reliant on working the east and west edges of the strike zone, with the ability to expand the zone as well as anyone in the game. Because of this, he has cemented himself into a high leverage role within the staff.

Additionally, this could be an interesting lens to predict what the Rays might be looking for as this year’s July 31 trade deadline approaches, as the O-Swing% leaderboard includes some familiar names like Josh Fleming, Diego Castillo and Ryan Thompson, indicating that this could be indicative of a skillset the Rays are looking for.