By any objective measure, Aroldis Chapman is one of the best relievers in baseball and most dominant single-inning forces in baseball history. Chapman has struck out 42.6% of the batters he’s faced in the big leagues, including 44.2% over the last five seasons, the highest rate in history by nearly two percentage points. Craig Kimbrel (40.7%) and Kenley Jansen (39.8%) are the only pitchers within nine percentage points of Chapman.
As good as he is, Chapman is not without his flaws as a pitcher. No player is perfect, after all. Chapman does walk a few too many hitters (career 11.