You may remember him as a LOOGY addition late last season.
This is not particularly good news for Glen Perkins, Brian Duensing or Anthony Slama, who are currently duking it out for the final bullpen slot. Neither of the two southpaws (Perkins and Duensing) are notably tough on left-handed hitters, and Slama is another right-hander.
If the Twins are going to open with a "bullpen by committee," they probably needed another lefty to use in matchups besides Mijares. Or if they expect to make Mijares the closer, then they need a LOOGY to fill that role in the seventh and eighth innings.