Right-hander Cody Eppley was optioned to Triple-A in a corresponding roster move. Eppley was one of three New York relievers that soaked up 7 1/3 innings in relief of a poor Freddy Garcia start on Saturday.
"He's another guy that can give you distance out of the bullpen," manager Joe Girardi said of Mitchell. "We thought we'd better have some more distance."
Along with Adam Warren, Mitchell was one of the finalists for the long relief job that went to David Phelps in Spring Training. Mitchell responded by going 2-1 with a 3.13 ERA in four starts at Triple-A, holding opponents to an 0.87 WHIP.
"I knew I was pretty close," Mitchell said. "I still knew I needed to pitch well and prove some things at the Triple-A level. I was fortunate enough to do that pretty early. It was only four starts, but I was lucky that they did call upon me when they needed someone. I'll just take it from there."