Jake Arrieta has thrown 10,362 pitches that have been tracked by the PITCHf/x system between 2008 and 2015, all of them occuring in the MLB Regular Season. In 2015, he has relied primarily on his Sinker (95mph) and Slider (90mph), also mixing in a Curve (80mph) and Fourseam Fastball (95mph). He also rarely throws a Change (89mph).
Basic description of 2015 pitches compared to other RHP:
His sinker generates more whiffs/swing compared to other pitchers' sinkers, has well above average velo, has less armside run than typical, has little sinking action compared to a true sinker and results in somewhat more groundballs compared to other pitchers' sinkers. His slider is thrown extremely hard, results in many more groundballs compared to other pitchers' sliders and has less than expected depth. His curve has an exceptional bite, is slightly harder than usual and has slight glove-side movement. His fourseam fastball generates an extremely high number of swings & misses compared to other pitchers' fourseamers, is a real worm killer that generates an extreme number of 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, has an obvious armside fade, is an extreme flyball pitch compared to other pitchers' changeups and has some natural sink to it.