NY gets right-handed pitchers Humberto Sanchez, Kevin Whelan and Anthony Claggett. It's a nice deal for New York given their relative lack of need for Sheffield. It's a nice deal for Detroit given their relative lack of need for starting pitching.
It's quite win-win on paper.
Sheffield signed a two-year extension with the Tigers as part of the deal. He's played for Leyland before, obviously, as one of the '97 Mercenary Marlins.