Sean Doolittle has thrown 5,577 pitches that have been tracked by the PITCHf/x system between 2012 and 2019, including pitches thrown in the MLB Regular Season, the MLB Postseason and Spring Training. In 2019, he has relied primarily on his Fourseam Fastball (94mph), also mixing in a Slider (81mph). He also rarely throws a Change (83mph).
Basic description of 2019 pitches compared to other LHP:
His fourseam fastball is straight as an arrow, generates a high number of swings & misses compared to other pitchers' fourseamers, has good "rising" action, has well above average velo and results in somewhat more flyballs compared to other pitchers' fourseamers. His slider sweeps across the zone and results in somewhat more flyballs compared to other pitchers' sliders. His change (take this with a grain of salt because he's only thrown 8 of them in 2019) generates a high number of swings & misses compared to other pitchers' changeups, is an extreme flyball pitch compared to other pitchers' changeups and has a lot of backspin.