With Cory Wade’s poor outings lately and Freddy Garcia’s transition to the rotation, the Yankees seemingly believed they could use another reliever. Qualls has previous experience pitching for contenders, not only for the Rays in 2010, but for the Astros in 2004-05.
Essentially, the Yankees have been short a relief pitcher, and apparently don't trust anybody in their farm system to fill that hole. Oddly, Qualls has recently had the same problem as Wade: home runs.
Wade's got a brilliant strikeout-to-walk ratio this season, but has given up six homers in 33 innings.
Qualls has a solid strikeout-to-walk ratio, but he's given up seven home runs in 32 innings.
I'm not sure Yankee Stadium's going to do Qualls any favors. In fact, I'm sure that it won't. But as bullpen depth, he's not useless to a first-place team like the Yankees.