As of today, Chris Perez is the Cardinals closer for 2009. However, there's a good chance that the Cardinals will end up signing a proven closer such as Trevor Hoffman or Takashi Saito between now and opening day. Would they be making a mistake to pass up the opportunity to sign a free agent, and let Perez keep the job?
The short answer is 'yes'. Perez simply doesn't have the control to be consistently successful at this point in his career. He walked 22 batters in 41.2 innings (while strikout out 42), and his minor league numbers suggest that his control may actually be a little worse than that. In addition, he allows a lot of flyballs (38.7% groundball rate). He is only 23 years old, so there's plenty of time for improvement, but at this point in Perez' career, St. Louis shouldn't be relying too heavily on him. If they do allow him to remain as their closer going into the season, keep an eye on the rest of their bullpen to see who might replace Perez when he falters.