AL Reliever of the Year: Craig Kimbrel, RHP, Red Sox
Craig Kimbrel recovered remarkably from his relatively down year in 2016, with a return to his electric, dominant self. He sported a 1.43 ERA and a 1.42 FIP in 69 innings with peripherals to match.
NL Reliever of the Year: Kenley Jansen, RHP, Dodgers
Jansen personified dominance all throughout the season, notching an absurd 1.32 ERA and 1.31 FIP. When he or KImbrel entered the game for their respective teams, the game was all but over.