One might've figured, following the Dan Haren trade to Anaheim, that the market was actually depressed, and that big-name players might be available for less than their rumored costs. According to the Cardinals, one would be wrong in assuming as much:
[Cardinals GM John] Mozeliak described any move as "certainly not imminent at this time," then hinted that the market may be too steep to find any significant upgrade for the rotation.
"We're continuing to explore avenues, but as we speak I can't say I'm encouraged."
Roy Oswalt negotiations with St. Louis have been hindered by the Astros not wanting to deal him within the division, the Astros seeking a high-level return, and Oswalt being under contract for so much money. If the Cards can't land him, then the rest of the market for them looks comparatively unappealing, and they may elect against making any move with Kyle Lohse and Brad Penny on the way back.
Meanwhile, it's unclear who might step up for Oswalt if the Cardinals drop out.