The Red Sox have signed the former Yankee reliever to a two year contract:

As for Mendoza, the Sox envision using him much like the Yankees did, mostly in a setup role, though he also could close and spot start.
”I wouldn’t be surprised if he pitches some of the most critical innings of the year for us,” Epstein said. ”His versatility and overall characteristics make him another really good quality option for Grady.”

Although Mendoza’s strikeout numbers aren’t high (5.32 per 9), but he walks no one and gives up very few HR. The Sox will need a good defense behind him, however, as he induces many more ground balls than fly balls.