Although he has not thrown an MLB pitch in 2019, Matt Harvey threw 12,389 pitches that were tracked by the PITCHf/x system between 2011 and 2018, including pitches thrown in the MLB Regular Season and the MLB Postseason. In 2018, he relied primarily on his Fourseam Fastball (95mph) and Slider (89mph), also mixing in a Change (88mph) and Curve (83mph). He also rarely threw a Sinker (93mph).
Basic description of 2018 pitches compared to other RHP:
His fourseam fastball has some natural sinking action, results in somewhat more groundballs compared to other pitchers' fourseamers, has slight armside run and has slightly above average velo. His slider is thrown extremely hard, has less than expected depth and has primarily 12-6 movement. His change generates fewer whiffs/swing compared to other pitchers' changeups, is much firmer than usual, has a lot of backspin and has slight armside fade. His curve is thrown extremely hard, has primarily 12-6 movement, has little depth and results in somewhat more flyballs compared to other pitchers' curves. His sinker (take this with a grain of salt because he's only thrown 7 of them in 2018) is basically never swung at and missed compared to other pitchers' sinkers, is an extreme flyball pitch compared to other pitchers' sinkers and has slightly above average velo.