To put it another way—in 2012, Cardinals shortstops hit .273/.331/.367, and the only reason they slugged .367 is that Pete Kozma slugged .577. Cardinals second basemen hit .240/.309/.363, thanks in large part to Skip Schumaker, who is not a second baseman, hitting .280/.330/.370.
To put it one more way—without Rafael Furcal the Cardinals' middle infield "base" is Daniel Descalso, who played 83 games at second and 24 at short. His numbers were boosted by the judicious application of a guy who'd just finished hitting .232 in Memphis and a fifth outfielder.
The Cardinals have some interesting middle infield prospects; Ryan Jackson is a plus shortstop, which would be nice, for a change, and Kolten Wong and Greg Garcia both look able to get on base. But none of them is ready to take Daniel Descalso's job, which is the primary offensive issue the Cardinals face going into 2013.
In the wake of the Cardinals' terminal three-game losing streak there's been a lot of talk about gaining more offensive consistency, and I don't think that kind of thing is possible in isolation; it's like an infomercial promising you can spot-reduce your way to a six-pack if only you strap yourself to a table you assembled out of a box and proceed to try to break it.
If you want a more consistent offense, take the one you have and then don't put Daniel Descalso and Pete Kozma into it. But aside from a Kelly Johnson best-fans-in-baseball flier I haven't seen a lot of options for cheap improvement presenting themselves.