Although they have not thrown an MLB pitch in 2023, Mark Leiter Jr. threw 3,059 pitches that were tracked by the PITCHf/x system between 2017 and 2022, all of them occuring in the MLB Regular Season. In 2022, they relied primarily on their Fourseam Fastball (91mph), Splitter (84mph) and Sinker (91mph), also mixing in a Curve (73mph), Cutter (88mph) and Slider (79mph).
In 2022, compared to other RHP:
His fourseam fastball results in somewhat more flyballs compared to other pitchers' fourseamers, has slightly below average velo and has slightly less natural movement than typical. His splitter generates an extremely high number of swings & misses compared to other pitchers' splitters, results in many more groundballs compared to other pitchers' splitters, has slight cut action and has some natural sink to it. His sinker has less armside run than typical. His curve has an exceptional bite, has below average velo, has primarily 12-6 movement and results in somewhat more groundballs compared to other pitchers' curves. His cutter results in somewhat more flyballs compared to other pitchers' cutters, has some natural sink and has strong cutting action. His slider comes in below hitting speed, is basically never swung at and missed compared to other pitchers' sliders, sweeps across the zone and has some two-plane movement.