Delving Into Mitch Keller’s 2019 Season

His ERA may have been ugly, but expectations should be high for Mitch Keller entering 2020

On Memorial Day, the Pittsburgh Pirates top prospect made their MLB debut. The highly touted prospect that made their debut that day was right-handed pitcher Mitch Keller. Keller struggled in that start, and some may say this was a sign of things to come for the Iowa native.

Keller went on to log 48 innings in 11 starts during the 2019 season. In these 11 starts, he posted a 7.13 ERA. Obviously, this is a less than optimal ERA for any pitcher. However, as can often be the case with pitchers, ERA did not tell the whole story for Keller in 2019.

With his pedigree, Keller has long been pegged as a future top of the rotation starting pitcher for the Pirates. While he had his struggles in some areas in 2019, others indicate that he is due to burst onto the scene in 2020 as said top of the rotation arm.

Other than ERA, Keller’s numbers in 2019 strong. The 23-year-old posted a 3.19 FIP, 7.1% walk rate and a 28.6% strikeout rate. While you would like to see his 1.13 HR/9 come down, this number was not astronomically high, either.

Keller was also burnt by batting average on balls in play. During the 2019 season Keller had a BAbip of .475. A BAbip over .300 indicates a pitcher that was burnt by bad luck and/or defense. A .475 BAbip is nowhere near sustainable, and bringing that down closer to the league average of .300 in 2020 alone will take a few runs off of Keller’s ERA.

During his 11 starts in 2019 Keller limited opposing batters to an average exit velocity of 87.2 MPH, which is better than the MLB average. This just further aligns with his BAbip being a result of bad luck/defense. Additionally, his fastball velocity, fastball spin rate and curveball spin rate were all better than league average as well. So, Keller certainly had the stuff in 2019 that is needed to be a top of the rotation starting pitcher.

Keller finished his 11 starts with a 1.3 fWAR. This would put him on pace for a 3.8 fWAR over the course of a normal 32 start season. A 3.8 fWAR would have ranked 13th among National League starting pitchers in 2019. Keller evolving into a top 15 starting pitcher in the NL is something that the Pirates would gladly welcome in 2020.

One issue with Keller in 2019 was his pitch selection. Keller’s two best pitches are his curveball and his slider. However, he only threw them a combined 36.9% of the time in 2019. Hopefully, with a new pitching coach and philosophy this will be corrected in 2020.

In 2019 Keller’s curveball generated a 25.5% swing and miss rate and limited opposing batters to a .133 slugging percentage. His slider evolved throughout the season to become a pitch that generated a 29.5% swing and miss rate, while limiting batters to a .274 slugging percentage. His third pitch, a four-seamed fastball, is the pitch he leaned on most throwing it 59.4% of the time. This was despite opposing batters slugging .719 off of his fastball.

Let’s hope that the Pirates’ new pitching coach realizes that a fastball heavy pitch to contact method is outdated and that they let Keller lean on his filthy curveball and slider in 2020.

Mitch Keller has all the tools needed to be a top of the rotation starting pitcher. During the 2019 season he flashed these tools, and pitched better than his ERA would indicate. Assuming the new pitching coach allows Keller to lean on his slider and curveball in 2020, it should be a big breakout season for the Pirates’ top prospect.