I'm going to start with the obvious point and then go into the measured counterpoints, instead of the other way around: Kelly Shoppach, in the wake of Yadier Molina's injury, seems like such a good fit with the St. Louis Cardinals. Not just in an abstract sense—they need a catcher, he's a catcher—but temporally, too. He became a free agent right as Molina became DL-bound, and Derrick Goold reported shortly afterward that the Cardinals at least made him an offer.
He's consistently above replacement level—his .196/.293/.346 line this year was good for an 84 OPS+, because Safeco—and he's not so good or so young that the Cardinals would be wasting excess resources on a guy who will ideally only be playing regularly for a couple of weeks.
If he does have to play regularly for longer than that, though, he seems a safe bet to have more upside than Tony Cruz; "low-OBP slugger" is an epithet for players at most positions, but at catcher it's a wise career move.
Measured Counterpoint 1: I have an admitted weakness for this kind of player, by which I mean bat-first backup catchers... on the downside of their career... named Kelly. So even if he weren't as perfect a fit as I believe Kelly Shoppach to be, I would probably be rooting for the Cardinals to sign him and give him a shot anyway.
Measured Counterpoint 2: Shoppach makes so much sense, given the information that we do have, that the Cardinals not signing him would lead me to believe they have other, more relevant information. This is the frustrating, question-begging nature of baseball blogs now that it's not 2003 and we don't assume all GMs are big dumb idiots.
Of course, I don't actually know what that disqualifying info would be. He's not a disaster behind the plate, and while it certainly wouldn't be uncommon for a catcher to lose it abruptly around his age-33 season, the gap between a Shoppach who hasn't lost it and the Cardinals' other options seems like a solid low-stakes bet.
It could be as simple as price. Goold's most recent update (scroll down) explains that the Cardinals' offer was a minor league deal, and that Shoppach and co. are going to look around for something better than that. I'm not sure they can find something better than that, but right now it looks like a simple gap in valuation.