The Twins were the subject of several bullpen-related trade rumors back in March when Joe Nathan was lost to Tommy John surgery. Rather than splurge to acquire a closer like Heath Bell, however, Minnesota instead elevated Jon Rauch to the closer's role and was rewarded with Rauch's 15 saves and 2.62 ERA.
While Rauch has pitched well enough to keep the closer's job, the Twins are still on the lookout for some help at the back of the bullpen. Ken Rosenthal and Jon Paul Morosi of FOXSports.com are reporting that the Twins are "monitoring" several relief options, most notably David Aardsma and Chad Qualls.
Aardsma's ERA stands at 5.21 in 20 appearances this season, though that ERA is inflated by a trio of poor outings. His peripheral numbers (a 1.21 WHIP, a K/9 rate of 8.5 and a 2.57 K-BB ratio) are solid. Qualls, meanwhile, has been the key figure in Arizona's bullpen woes this season. His ERA currently sits at 7.77 following today's disastrous outing against Atlanta --- Qualls allowed four ninth-inning runs in just a third of an inning pitched.
With these numbers and familiarity with American League batters, Aardsma has to be considered the stronger option for Minnesota if they were to make a move. The only point in Qualls' favor is that he's in the last year of his contract, whereas Aardsma is making $2.75MM this season and is under team control through 2012. The cost-conscious Twins may not like the idea of giving Aardsma an arbitration raise in the winter if he's just going to be a set-up man, though Minnesota could also hold onto him if Rauch struggles or perhaps trade him to another reliever-hungry team in the offseason.
Qualls is due to earn $4.185MM so he'd cost more in payroll, but the Twins could just let him walk after the season if need be. Also, Arizona's asking price would certainly be less than what Seattle would want for Aardsma.