Although he has not thrown an MLB pitch in 2018, Williams Perez threw 2,726 pitches that were tracked by the PITCHf/x system between 2015 and 2016, all of them occuring in the MLB Regular Season. In 2016, he relied primarily on his Sinker (92mph), also mixing in a Curve (78mph), Change (80mph) and Fourseam Fastball (93mph).
Basic description of 2016 pitches compared to other RHP:
His sinker has slight armside run. His curve has little depth and results in somewhat more groundballs compared to other pitchers' curves. His change has below average velo, results in somewhat more flyballs compared to other pitchers' changeups and has some natural sink to it. His fourseam fastball is a real worm killer that generates an extreme number of groundballs compared to other pitchers' fourseamers, has an obvious tail, has some natural sinking action and has essentially average velo.