Closer: Roberto Osuna, Toronto Blue Jays, current age 20.268
Regular season stats: 68 games, 69.2 IP, 20-for-23 saves, 2.58 ERA, 9.7 K/9, 2.1 BB/9
Postseason stats: 7 games, 8.1 IP, 1 save, 2.16 ERA, 6.5 K/9, 3.4 BB/9
Osuna’s postseason ended on a sour note, as he took the loss in the deciding Game 6 of the ALCS. Still, quite an impressive rookie season for the youngest player on this list. Osuna was poised all year upon being handed the closer’s role. It is rather unheard of for a playoff contender to give the final three outs to a rookie, let alone a 20-year-old, but Osuna more than lived up to the task.