Mitchell was using crutches on Thursday morning and has been scheduled to see Dr. Robert Anderson in Charlotte, N.C., on Monday, with surgery considered to be a possibility.
"A freak injury. It's just part of it," Mitchell said. "You just kind of have to roll with it. I can't get too down on myself. Luckily it's not my arm, so I'll take that."
Mitchell had already been informed that the Yanks planned to carry him on the 25-man roster, likely in the bullpen. He compiled a 0.57 ERA in 15 2/3 spring innings, allowing one run and seven hits with three walks and 12 strikeouts.
YES Network's Jack Curry reported that Mitchell will miss a minimum of three months. Mitchell said that he would not have a timetable until he visits with Anderson, who also treated Derek Jeter after his ankle fracture in the 2012 postseason.
Mitchell's diagnosis came on the heels of the news that Andrew Miller, who is to be the Yankees' closer until Aroldis Chapman returns from suspension in May, has a chip fracture in his right wrist, which was struck by a line drive on Wednesday. Miller, a left-hander, said he intends to pitch with the injury.
Johnny Barbato, Luis Cessa and Kirby Yates are thought to be the final contenders for bullpen spots. Manager Joe Girardi has said that he hopes to announce all of his decisions on Thursday.
"It's crazy. I'm not trying to be too roller-coaster right now," Mitchell said. "You just have to roll with it. It's just a bump in the road and we'll get past it, hopefully quicker than later."
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.