Although he has not thrown an MLB pitch in 2019, Hector Rondon threw 6,098 pitches that were tracked by the PITCHf/x system between 2008 and 2018, including pitches thrown in the MLB Regular Season, the MLB Postseason, The World Baseball Classic and Spring Training. In 2018, he relied primarily on his Fourseam Fastball (98mph) and Slider (87mph), also mixing in a Sinker (98mph). He also rarely threw a Change (92mph).
Basic description of 2018 pitches compared to other RHP:
His fourseam fastball generates a high number of swings & misses compared to other pitchers' fourseamers and is blazing fast. His slider generates more whiffs/swing compared to other pitchers' sliders, is much harder than usual, results in somewhat more groundballs compared to other pitchers' sliders and has some two-plane movement. His sinker is thrown at a speed that's borderline unfair and results in somewhat more groundballs compared to other pitchers' sinkers. His change is thrown extremely hard, is basically never swung at and missed compared to other pitchers' changeups, results in more flyballs compared to other pitchers' changeups, has slight armside fade and has some natural sink to it.