Pittsburgh Pirates Prospects: Best Pitching Tools

Slider – Mitch Keller

MLB Pipeline: 50

FanGraphs: 60, future 60

Now, yes, Cody Bolton has a better grade according to MLB Pipeline, but we can make it easier to judge Mitch Keller because we can see the movement and results on the pitch in the Majors through Baseball Savant.

Keller’s slider sits with 35.9 inches of vertical movement and 4.1 inches of horizontal break. Both of which are better than the MLB average. Keller also has a fastball, change up, and curveball to complement the slider. At the MLB level, it was his best pitch as he put away 29.5% of all batters he faced with it, and opponents slugged just .235 against the pitch.

Keller was one of the best, if not the best, pitcher at the Triple-A level last season. In 103.2 innings, Keller held batters to a 3.56 ERA, 1.24 WHIP and a 3.60 FIP. That also includes a strong 28.2% strikeout rate and just an 8% walk rate. He also allowed just nine home runs, and induced ground balls at a solid 44.7% rate. Among Triple-A pitchers with at least 100 innings pitched, Keller was top three in ERA (3rd), FIP (1st), WHIP (3rd), strikeout rate (1st), HR/9 (1st), K/BB rate (tied for 1st), and batting average against (3rd).

Despite not putting up as good of run prevention numbers at the Major League level, he was really hurt by bad defense and a .475 batting average on balls in play. However, he still struck out 65 of the 227 batters he faced, and walked only 16. He also gave up only six home runs, resulting in a solid 1.1 HR/9. Keller still carried strong ERA predictors including a 3.19 FIP, 3.78 SIERA, 3.47 xFIP, and 4.13 DRA. He also sat in the top 69th percentile in exit velocity and top 59th percentile of hard hit rate. Overall, opponents were projected to have a .265 batting average against, but, in reality, they hit for a .343 average impart due to that BAbip.