Pittsburgh Pirates: Examining What’s Gone Wrong With Mitch Keller

After showing a ton of promise in his first taste of big-league action in 2019, Mitch Keller has seen his stock take a large hit since. So what happened to the Pirates’ pitcher?

Pittsburgh Pirates right-handed pitcher Mitch Keller was once considered one of baseball’s premier pitching prospects. His first taste of MLB action in 2019 only reinforced his potential, despite him posting literally the highest BAbip in MLB history. However, through three Keller’s 2021 season has been nothing short of hard to watch. So what happened to this once highly promising pitcher?

In 2019 Keller looked outstanding at Triple-A. In 103.2 innings, the then top prospect had a 3.56 ERA, 3.60 FIP and 1.12 WHIP. His ERA was the 4th best in the league, was 1st in FIP and 5th in WHIP. Keller had an outstanding 28.2% strikeout rate and a 0.72 HR/9 rate. The former, he led all Triple-A pitchers in and the ladder he ranked 2nd.

When the Pittsburgh Pirates proved Keller to the Major League level he put up an ugly 7.13 ERA and 1.83 WHIP, but was severely hurt by a .475 batting average on balls in play. In the history of baseball, that is the highest single-season BAbip by any pitcher to throw at least 40 innings (Keller tossed 48).

Aside from that super unlucky BAbip he continued to strike out batters at a strong 28.6% rate, kept free passes to just a 7.0% mark, and home runs at a 1.13-per-9 rate. Keller had a very solid 3.19 FIP, 3.47 xFIP, 3.78 SIERA and 2.76 ERA to go with his strong perpherials. He was also in the top 96th percentile of expected wOBA and expected wOBA on contact (xwOBACON).

Fast forward to 2021 and Keller looks nothing like the pitcher with the high upside we saw in 2019. What changed between 2019 and 2021 that has brought Keller so far down? One major issue is that he’s lost over an inch of movement off his slider. In 2019, his slider had 35.9 inches of vertical drop however that has sat at just 34.4 inches in 2021.

He’s also lost some speed off his fastball. He averaged about 95.4 MPH in 2019 but just 94.8 MPH this year. However, the biggest potential culprit has been a major decrease in his spin rate. Keller’s fastball averaged 2473 RPM in 2019, but now it’s down to just 2361 RPM. His slider has taken an even bigger hit. This pitch sat around 2661 RPM, but now has less spin than his fastball at 2353 RPM. His curveball lost 97 RPM of spin and his change-up is down 28 RPM from 2019. To go with the decreased spin, all of his offerings have lost velocity as well.

He’s also changed where he works in the zone. In 2019, Mitch threw his slider down and in on the right side of the plate most often but now works down and through the middle. His fastball would usually work inside toward the left-hander’s batters box but now works up and in the middle of the zone. He’s also had issues getting his curveball into the zone, something that wasn’t as much of an issue in 2019, and his change-up is all over the place.

In all, it could be something mechanical, it could be something mental, or a mix of both. I tend to believe it could be a bit of both. Last year, Keller missed a decent amount of time to an injury. Maybe in trying to compensate for a small decrease in velocity, he’s trying too hard and over-adjusting, trying to add more spin and movement but ending up doing neither. Maybe he’s just trying too hard in general.

Where does this leave Keller? He’s still a young pitcher. He turned 25-years-old at the beginning of April, so all hope isn’t lost yet despite his heavy struggles. For all we know, he might just need to re-adjust his arm slot and change his grip a bit. However, it’s still hard to watch someone that once showed so much promise in his first taste of MLB action struggle so badly.