Only tangling a metaphor will help me understand this, so here goes: The St. Louis Cardinals are a car. They're a nice car—fast, reliable, extremely efficient—but one of their tires is looking a little pekid, and the spare in the trunk is Pete Kozma. I mean, it's not very well-inflated itself. So I'm struggling to understand why the only item on the Cardinals' list at Pep Boys is a second set of a dice to wrap around their rear-view mirror. That is, the Cardinals have some very real problems, but all Derrick Goold et al have managed to pry from John Mozeliak is that they're pretty interested in adding another left-handed reliever to the bullpen.
Situational relievers have value, don't get me wrong. They just don't have much of it. As shaky as Barret Browning, J.C. Romero, and Sam Freeman all were, they combined for less than 50 innings, most of them low-leverage. A left-handed reliever isn't much use in an emergency, either; a utility infielder might be pressed into service at second, short, or third as a starter, but a second-lefty-reliever can only find himself promoted to first-lefty-reliever.
If Mozeliak is really convinced—by metrics, by a psychological evaluation, by a personal relationship, whatever—that an extra southpaw will help Marc Rzepczynski regain his effectiveness, then it makes sense to eke an extra half-win out of the spot where the Mystery Reliever at the back of the pen would otherwise sit. But this team doesn't yet seem solid enough to focus on the difference between pink fuzzy dice (Mike Gonzalez, maybe?) and green.