Although he has not thrown an MLB pitch in 2020, David Hernandez threw 11,299 pitches that were tracked by the PITCHf/x system between 2009 and 2019, including pitches thrown in the MLB Regular Season, the MLB Postseason, The World Baseball Classic and Spring Training. In 2019, he relied primarily on his Cutter (86mph), Sinker (94mph) and Fourseam Fastball (94mph), also mixing in a Curve (82mph). He also rarely threw a Change (88mph).
Basic description of 2019 pitches compared to other RHP:
His cutter generates an extremely high number of swings & misses compared to other pitchers' cutters, has heavy sink, is an extreme flyball pitch compared to other pitchers' cutters and has slightly below average velo. His sinker generates more whiffs/swing compared to other pitchers' sinkers, results in more flyballs compared to other pitchers' sinkers, has less armside run than typical, has little sinking action compared to a true sinker and has slightly above average velo. His fourseam fastball generates an extremely high number of swings & misses compared to other pitchers' fourseamers, has essentially average velo and has slight armside run. His curve is much harder than usual, has little depth and has primarily 12-6 movement. His change (take this with a grain of salt because he's only thrown 2 of them in 2019) is basically never swung at and missed compared to other pitchers' changeups, is much firmer than usual, results in more flyballs compared to other pitchers' changeups and has a lot of backspin.