Not only does the acquisition of Denns Reyes improve the left side of the Cardinals bullpen, it is going to make it better by ratcheting up the pressure to perform for lefties and righties alike.
Why? Well, I'm not convinced that the Redbirds have written in stone that the team will only carry two lefty bullpenners.
If Chris Perez wins the closer job and Ryan Franklin is the setup man, would it be better for Jason Motte to work as a mop up man in St. Louis or as the closer in Memphis? Would it be better for him to try to hone an off speed pitch in a pressure situation during a meaningful game or in a much less meaningful game in the minors?
What if Chris Carpenter or another starter gets injured? Kyle McClellan would most likely move from the 'pen to the rotation. In that scenario, Motte could make the team AND it could still keep a third lefty.
Closer: Perez or Motte