Keller basically stopped throwing his changeup last season, dropping its usage rate from 4.1% all the way to 1.99%.
Keller throws both a four-seam fastball and a sinker, averaging 93.35 mph with both. He struggled a bit more inducing ground balls with them compared to 2018 but still managed to end the season with a 50% ground-ball rate.
Already Keller’s secondary pitch during his rookie season, he bumped its usage from 26.2% to 31.68% in 2019. He also managed to take some of the pace off it, down to 84.84 mph compared to 85.9 mph the previous season.
Keller’s four-seam fastball limited batters to a slash line of .266/.360/.348 in 2018. It was not a standout pitch, but it was certainly not a negative for Keller.
The slider is Keller’s put-away pitch, as he mostly kept it out of the strike zone. A 13.7% whiff rate isn’t incredible but still solid, and its .276 slugging allowed made it a great contact manager.
Keller’s two-seam fastball is a ground-ball machine. He kept 65.5% of its batted balls on the ground. A .253 BABIP my be unsustainable, but its weak contact abilities made it a plus pitch for Keller.
Keller hardly utilized his changeup, throwing just 86 of them. It was knocked around to a .521 wOBA in that small sample.