Jake Arrieta has thrown 20,300 pitches that have been tracked by the PITCHf/x system between 2008 and 2018, including pitches thrown in the MLB Regular Season, the MLB Postseason and Spring Training. In 2018, he has relied primarily on his Sinker (93mph), also mixing in a Curve (80mph), Slider (90mph) and Change (88mph). He also rarely throws a Fourseam Fastball (93mph).
Basic description of 2018 pitches compared to other RHP:
His sinker has slight armside run and has slightly above average velo. His curve has a sharp downward bite, is slightly harder than usual and has slight glove-side movement. His slider is thrown extremely hard and has less than expected depth. His change dives down out of the zone, generates fewer whiffs/swing compared to other pitchers' changeups, is much firmer than usual, results in many more groundballs compared to other pitchers' changeups and has slight armside fade. His fourseam fastball (take this with a grain of salt because he's only thrown 17 of them in 2018) generates an extremely high number of swings & misses compared to other pitchers' fourseamers, is an extreme flyball pitch compared to other pitchers' fourseamers and has essentially average velo.