The key to making the 49ers' game-day roster this season: versatility. That's what a number of the team's offensive linemen are working on this spring. The most prominent is Alex Boone, who is the frontrunner for the starting right guard position but who on Tuesday lined up at right tackle in starter Anthony Davis' absence.
This mimicked a regular-season scenario in which Davis - or left tackle Joe Staley - went down with an injury. Boone, who was the team's backup tackle last season, would move from the starting guard position to tackle, and someone from the bench would have to fill in at guard.
Most teams activate seven offensive linemen on game days. The two players on the bench ideally are versatile, and in the 49ers' case, one of them needs to be able to play center. Daniel Kilgore has been lining up exclusively at center this spring, at least in the two practices that have been open to the media. He played guard last year.
On Tuesday, Mike Person filled in at right guard with the first-string unit. Person played tackle in college and mostly lined up at tackle as a rookie last season. He's also played a lot at tackle during the recent OTAs. If the season began today, Kilgore (center and guard) and Person (guard and tackle) likely would be the two backup offensive linemen who are active on game day.
Last year the 49ers kept nine offensive linemen on the 53-man roster. Boone and Chilo Rachal were the game-day backups while Kilgore and Person usually were inactive on game days. The question this offseason is, A) which offensive linemen will fill those final spots and, B) whether the team even needs nine offensive linemen. With an influx of running backs and wide receivers in the offseason, the team could open a roster spot by keeping only eight linemen this year.
Among the remaining offensive linemen are fourth-round pick Joe Looney, a guard who also has some experience at center, and sixth-round pick Jason Slowey, who played tackle in college but has been a center this season. Meanwhile, 2011 practice squadders Derek Hall, who can play tackle, guard and center, and center Chase Beeler also are in the mix.
The 49ers also may be able to save a spot by keeping one fewer defensive lineman. Last season they had seven at one point, which is a lot for a 3-4 defense. Ian Williams and Will Tukuafu are eligible for the practice squad.
-- Matt Barrows