Boone is entering the fourth year of a five-year deal and is slated to count $2.6 million against the cap next season. All of the 49ers starting offensive lineman will earn more money next year, except for C Daniel Kilgore.
Boone moved from tackle to guard two seasons ago. The move paid off in a big way for the 49ers, as Boone graded out as the No. 3 guard in the 2012 season according to Pro Football Focus. He regressed slightly last year, but still graded out respectably at No. 40 out of 81 qualifiers.
Despite his success, it may be difficult for San Francisco to give Boone the extension he seeks. The team has reportedly been trying to negotiate a new deal with QB Colin Kaepernick this off-season, and guys like WR Michael Crabtree and G Mike Iupati are also scheduled to hit the market after next season.
Additionally, the entrenched talent on the San Francisco offensive line may necessitate allocating funds elsewhere. Tackles Joe Staley and Anthony Davis have both signed long-term deals, and the aforementioned Iupati is one of the best guards in the league.
San Francisco drafted C Marcus Martin and G Brandon Thomas, so they have some options to work with in the coming years if they choose to let this situation play out.