According to a major league source, the Red Sox have signed infielder Nick Punto to a two-year, $3 million deal. Multiple reports add that Punto can make an additional $500,000 in incentives.

Punto, 34, represents an above-average defensive third baseman and shortstop who will give the Sox a strong glove either for the late innings or in case shortstop Marco Scutaro or third baseman Kevin Youkilis is injured. In 68 games last year with the championship Cardinals, Punto hit .278 with a .388 OBP, .421 slugging mark and .809 OPS, all career bests. However, in his career, he is a more modest .249/.325/.327/.652 hitter in parts of 11 seasons with the Phillies, Twins and Cardinals who has never hit more than four homers in a season.

While Punto’s defense was the primary asset that led the Sox to sign him (once they dealt infielder Jed Lowrie to the Astros in the Mark Melancon deal), he is also regarded as a strong veteran clubhouse presence, and one who will be comfortable in his backup role. Undoubtedly, the Sox would have preferred a one-year deal for a utility player, but the market escalated early for players in such roles this offseason, with two-year deals going to players such as John McDonald, Willie Bloomquist, Jamey Carroll, Clint Barmes, Laynce Nix and Jerry Hairston.

That, in turn, set the bar at two years for Punto (who played on a one-year, $750,000 deal last year), who will help the Sox address some of the concerns that existed about their left-side infield defense — concerns that became pronounced in September, when Kevin Youkilis was limited significantly by his sports hernia and hip issues and Lowrie and Mike Aviles both struggled in his place.

Among the many factors that led to the team’s collapse in the final month, one of the most overlooked was their brutal defense. In September, the team gave up a .343 batting average on balls in play, tied for the worst mark in the American League that month and 45 points worse than the team’s season-long BABIP of .288. The team’s 13 unearned runs in September were second most in the American League.