The all-time single season performance Mariners rotation

Oakland Athletics v Seattle Mariners
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Mariners 2013 Hisashi Iwakuma

Iwakuma only spent six years in MLB, but by far, his best season was his fantastic performance in ‘13. His 7.0 WAR was by far the best of his relatively short career, and the season was his lone All-Star Game nod and his third-place Cy Young Award finish was the one time he got votes for the Award.

The righty from Japan went 14-6 with a 2.66 ERA, pitching 216.2 innings and striking out 185 batters to 42 walks. His 138 ERA+ was the best of his career and one of four seasons, he was an above-average pitcher. 

While he does not have the longevity or prolonged success to make the Mariners’ Hall of Fame, his ‘13 season deserves a spot on this list.