The 49ers' giant insurance policy at guard

Quite a few veteran guards filtered through San Francisco 49ers headquarters this offseason.

Most signed elsewhere.

Leonard Davis, listed at 6-foot-6 and 375 pounds, remained available until Thursday, when the 49ers signed the former Arizona Cardinals and Dallas Cowboys starter to a one-year deal. Davis, 33, was a starter every year from 2001 through the 2010 season, but he played zero snaps for Detroit after signing with the team during last season.

Davis' age, weight and time away from the game raise natural concerns. If all goes to plan, the 49ers will not need him at right guard, the one position on the line without a returning starter after the team parted with Adam Snyder and Chilo Rachal.

Alex Boone projects as the starter on the right side. The team has sounded pleased with his transition from tackle. The other candidate for the job, Daniel Kilgore, also lacks experience. And with rookie Joe Looney recovering from serious foot surgery, the team could use other contingencies at guard. Looney, a fourth-round draft choice this year, suffered a Lisfranc fracture during Senior Bowl week. It's unclear when he'll be ready to contribute.