April 2017 Tommy John surgery cost Jefferies almost two full seasons. His below-average recovery time was worrisome, but he came back with a vengeance, logging a 93:9 K:BB in 79 innings, primarily at Double-A. The No. 37 overall pick in 2016 sat at 95 mph with his fastball in his final start of the year and had his signature plus changeup working throughout his first full campaign. The A's were very careful with him -- he threw between three and 3.2 innings in all 26 appearances -- so his numbers are a little inflated due to the fact that he never had to face the same hitter more than twice. The 6-foot, 185-pound righty still needs to prove he can handle a starter's workload and needs to sharpen his breaking ball. Even so, the potential for a plus fastball, plus changeup and plus command from a pitcher who should join the big-league rotation this summer makes him relevant in all formats. Read Past Outlooks