JUPITER, Fla. -- Last spring, the Cardinals came to Spring Training hopeful of watching Matt Carpenter take the reins of the second-base job. This year, the organization could leave here with assurances that he is part of its long-term core.

The Cardinals are reportedly in the process of negotiating a multi-year deal with Carpenter, even though the 28-year-old infielder is already under team control for another four years. The St. Louis Post-Dispatch first reported discussions taking place. Ken Rosenthal of FOXSports.com followed that up by tweeting that the two sides are focused on a six-year deal that if completed would be worth $50-55 million. The club has not commented on the reports.

Carpenter, who traveled to Fort Myers, Fla., on Thursday for the Cardinals' rained-out game against the Twins, would not confirm that negotiations were ongoing, but offered the following statement: "If we have discussed it and if it happens, I would be extremely grateful."

Manager Mike Matheny said: "It's one of those great stories for a guy that didn't necessarily have the golden road paved for him. He's come in, he's worked his butt off and he's done a real nice job. I know the conversations have started and hopefully they'll continue."

Should the Cardinals complete a multi-year deal with Carpenter this month, it will mark the third straight spring in which they have signed a core player to an extension. Yadier Molina inked his current five-year deal in 2012. Last year, both Adam Wainwright and Allen Craig accepted multi-year offers.

A six-year deal would buy out Carpenter's final pre-arbitration year, three arbitration seasons and his first two years of free agency. He made $504,000 in 2013, and he would have his contract renewed at a slightly higher salary if no multi-year agreement is reached this spring.

Carpenter is on the heels of a breakout season in which he was a first-time All-Star and top-four finisher in the National League Most Valuable Player balloting. He led the Majors in hits (199), runs scored (126) and doubles (55), while filling holes for the Cardinals at second base and in the leadoff spot.

After one season at second, Carpenter is moving back to third base, his natural position, this year. The Cardinals needed to find a new third baseman after trading David Freese to Anaheim in November. By moving Carpenter, the Cardinals have also opened up a position for prospect Kolten Wong.