Although he has not thrown an MLB pitch in 2016, Jake Arrieta threw 13,147 pitches that were tracked by the PITCHf/x system between 2008 and 2015, including pitches thrown in the MLB Regular Season and the MLB Postseason. In 2015, he relied primarily on his Sinker (95mph) and Slider (91mph), also mixing in a Curve (81mph) and Fourseam Fastball (95mph). He also rarely threw a Change (90mph).
Basic description of 2015 pitches compared to other RHP:
His sinker generates a high number of swings & misses compared to other pitchers' sinkers, generates a very high amount of groundballs compared to other pitchers' sinkers, has well above average velo, has less armside run than typical and has little sinking action compared to a true sinker. His slider is thrown extremely hard, generates a very high amount of groundballs compared to other pitchers' sliders and has less than expected depth. His curve generates more whiffs/swing compared to other pitchers' curves, has a sharp downward bite and is slightly harder than usual. His fourseam fastball results in somewhat more groundballs compared to other pitchers' fourseamers, has slightly above average velo and has slightly less natural movement than typical. His change is thrown extremely hard, is a real worm killer that generates an extreme number of groundballs compared to other pitchers' changeups, has slight armside fade and has some natural sink to it.