Similar to the slider, Doolittle’s changeup is utilized under 10% of the time. It’s not a great pitch, and he has trouble locating it, evidenced by a 30% zone rate. Doolittle should increase the usage of his slider and essentially eliminate his changeup.
Doolittle has one of the most extreme fastball-heavy arsenals, throwing the heater 88% of the time. His velocity continues to decline ever so slightly over the last several seasons, which could have contributed to a decrease in performance. He was bitten by the home-run ball with a double-digit HR/FB% in 2019 against the fastball. He also gave up a lot more contact as the SwStr% dropped by 5.2% in 2019. Doolittle’s primary offering went from elite to just good in 2019.
Obviously, Doolittle’s slider isn’t a large part of his game, but it’s provided positive pVals in each of the last three seasons. It generated a near-20% swinging-strike rate in 2019 and induces weak contact. If Doolittle’s fastball ever starts to slip, he has a solid secondary pitch to fall back on.
Doolittle almost exclusively uses the four-seam fastball and for good reason. The pitch generated .142 batting average against with a near 38% strikeout rate. Despite elite numbers against, he lost one mph on the pitch and its horizontal arm-side run started to dwindle.
Doolittle ditched the splitter and went to the changeup as his primary offspeed pitch in 2017. It generated a high percentage of ground balls and a miniscule .100 batting average against in 2018.
The slider is used infrequently, but is a plus pitch for Doolittle. It gets swings and misses outside the zone and has not allowed a base hit in the last 66 pitches thrown. The slider is most effective because it keeps hitters off balance with a 12 mph velocity differential from the four-seamer.