The Boston Red Sox have emerged as a primary contestant in the Roy Oswalt sweepstakes, but MLB rumors sites like MLBTR won't let the St. Louis Cardinals off the hook on signing a sixth starter that easily—they're still being run through as a potential spoiler in the Oswalt contest, which has gotten increasingly affordable in the last few months.
Current rumors suggest Oswalt might be as cheap as one year, $8.5 million, which would be hard to resist even though the Cardinals are already paying Jake Westbrook and Kyle Lohse more money than that to stand at the back of their relatively expensive rotation. Oswalt's coming off one of his least consistent seasons as a Major League starter, but he's still coming off a Roy Oswalt season—two walks per nine inning, at all costs.
Oswalt would be an upgrade for the Cardinals, but before they signed him they'd have to know they had someplace to shift Lohse or, more likely, Westbrook to somebody else who's willing to pay some of his salary.