Rumbelow will undergo Tommy John surgery and likely miss the entire 2016 season, Chad Jennings of the Westchester Journal-News reports.
Rumbelow left Triple-A Scranton/Wilkes Barre's game Sunday after heading to the mound to start the fifth inning. The loss of the righty hurts the Yankees' bullpen depth as he would have likely been promoted to the big leagues at some point this year had he not gotten injured. The 24-year-old carries a career 3.21 ERA over 134.2 innings in the minors along with 158 strikeouts and is considered to be one of the Yankees' more promising pitching prospects.