TJ Stuff: All Gaus, No Breaks

Kevin Gausman, Mitch Keller

Welcome to “TJ Stuff”, a series which aims to highlight any intriguing MLB players and performances.

Kevin Gausman

Kevin Gausman has started off hot with a 2.33 ERA and 3.43 FIP across 19.1 IP, a complete reversal of his slow start in 2024. Looking at his pitch data we can get a good sense of what changed and we can conclude that 2023 Gausman is shining through!

The frigid temperature in Boston likely played a part into his depressed velocity yesterday (92.8 MPH), so I won’t read too much that dip as his two prior starts had him averaging 94.6 MPH on his fastball. This is ~0.5 MPH increase compared to 2024 and lines him up with his 2023 velocity. Another aspect of his fastball that looks improved is its iVB. The offering is averaging 18.7” iVB, a +1.7” increase compared to last season. Considering both the increase in velocity and iVB, it is safe to say that Gausman’s fastball looks significantly better, and tjStuff+ agrees. Its grade hopped from 105 to 108 tjStuff+ and it has been effective at generating whiffs early on.

We have also seen improvements to both his splitter and slider. The splitter improvement is more indirect as its shape hasn’t change much other than some additional arm-side run. The extra vertical separation from his fastball helped the splitter jump from a 99 tjStuff+ pitch to 105 tjStuff+. His slider saw a similar improvement as its shape has exhibited more ride than his 2024 slider. Overall, his tjStuff+ has increased from 101 to 106 and he continues to display top tier command.

Gausman is turning back the clock this season and performing like the ace the Jays signed him as 3 years ago. I don’t expect the elite strikeout rate to return, but he should provide plenty of value out of Toronto’s rotation.

Mitch Keller

It hasn’t been the hottest start to the season for Mitch Keller but he has made a bunch of changes that portend stronger production. The biggest change comes in the form of his pitch usage. Last season he rarely threw his changeup (<1%), and in the early going this season that is up to 15% vs LHH. He hasn’t shown the best feel for the offering as he struggles to locate it down in the zone, but its shape is excellent. The offering sits in the high 80s with 15” HB and 1” iVB with some reaching as far down as -5” iVB. The vertical separation from his fastball is particularly deadly to LHH who expect a high rising heater. It’s been a while since he has thrown his changeup regularly in game, so I am expecting the inefficiencies to stick for a bit. Once those clear up it could very well be his most valuable offering.

Another change Keller made to his usage was the removal of his cutter. Last season it returned a -4 Run Value. Its poor performance can be attributed to its inability to generate whiffs. My theory is that it the pitch blended too much with his slider that it didn’t have a distinct movement profile which allowed batters to pick up on it more easily.

Overall, Keller has made some tweaks too his arsenal to optimize pitch movement. His tjStuff+ is up from 102 to 104 on the season and his changeup seeing the largest bump (102 to 110). One thing I would like to see increase from Keller is his sinker usage vs RHH. It was an effective damage mitigating tool last season, yet he has greatly reduced its usage (33% to 19% vs RHH). Keller has a 6-pitch mix which grades out well and he has exhibited a proficient ability to attack the zone early on in the season. With some time and a few tweaks to his usage I could see him returning a fairly productive season for Pittsburgh.

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