In 2014 and 2015, Dellin Betances put together one of the best two year stretches of relief pitching in history. Over his first two full seasons with the Yankees, he maintained a 1.45 ERA and struck out 39.5% of the batters he faced. Betances managed these feats despite easily leading all relievers in innings these past two years, totaling a startling 174 innings. To dominate so thoroughly, so frequently, during a time when the best relievers are often reserved exclusively for three-out save situations, is practically unheard of. In fact, during the wild-card era, no reliever has posted a season with more innings and a better ERA+ than Betances has had in both 2014 and 2015, according to Baseball Reference:
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Yet, during the second half of 2015, Betances exhibited notable signs of decline.