Benoit, 36, figures to serve as Huston Street's setup man even though he saved 24 games for the Tigers in 2013. Benoit has a 2.53 ERA (164 ERA+) in 259 1/3 innings since returning from major shoulder trouble four years ago. He's been one of the best late-inning relievers in the game.
Fellow free agent closer Grant Balfour signed with the Orioles for a similar two-year, $15 million contract on Tuesday. The Padres traded Luke Gregerson to Athletics two weeks ago and needed another reliever to solidify the bullpen.