11:50am: Carpenter's deal will be worth $50-55MM if completed, Rosenthal tweets.
11:17am: The Cardinals and Carpenter are closing in on an extension of "significant length," sources tell Jon Heyman of CBS Sports. The deal is believed to buy out all three of his arbitration seasons and at least one free agent season, "and probably more than that," according to Heyman.
12:06am: The Cardinals are talking with Matt Carpenter about a long-term contract extension, Derrick Goold of the St. Louis Post-Dispatch reports. Cards GM John Mozeliak confirmed that he had been in contact with Carpenter's agents at SSG, and though the general manager gave no hint as to whether or not a deal was close, Goold said that Carpenter left the club's Spring Training facility in the middle of Wednesday's game, "presumably to have a physical."
2013 was Carpenter's first full season as a Major Leaguer and he delivered in style, hitting .318/.392/.481 with 11 homers and leading the league in runs (126), doubles (55) and hits (199) while producing 7.0 fWAR and 6.6 rWAR. He did all of this while playing primarily as a second baseman, a position Carpenter had never played as a professional before last year (he'll move back to third base this season). This spectacular campaign earned Carpenter his first All-Star appearance, an NL Silver Slugger Award and a fourth-place finish in NL MVP voting.
Carpenter was also one of baseball's top bargains, as he did all that while still playing for around the league minimum. He isn't eligible for arbitration until next winter and the Cards have him under team control through the 2017 season, and an extension would give St. Louis some cost-certainty through those three arb years. Since Carpenter isn't eligible for free agency until his age-31 season is over, a multiyear pact would give him security now rather than risk missing his chance at a big contract if he's already seen as being on the decline once he hits the open market. This isn't to say that Carpenter will be at a negotiating disadvantage, of course, as he's still coming off an elite season.