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Jonathan Martin played nothing but tackle in his 23 games with the Miami Dolphins. But his versatility could be tested with the 49ers.
Martin is in the picture to serve as the 49ers' swing tackle -- the backup on both sides of the line. He is also expected to spend a lot of the offseason working on his strength to see action at both guard positions, a source told CSNBayArea.com on Tuesday night.
Martin's clearest path to eventually earning a starting role with the 49ers could be at guard. Left guard Mike Iupati is signed through the 2014 season, and right guard Alex Boone is under contract for two more seasons.
Meanwhile, left tackle Joe Staley is signed through 2017, and right tackle Anthony Davis is under contract for six more seasons.
Daniel Kilgore and Adam Snyder were the 49ers' top backups last season. Kilgore is slated to take over for Jonathan Goodwin as the 49ers' starting center after signing a three-year contract extension on Feb. 21. Joe Looney and Ryan Seymour were also reserve guards on the 53-man roster.
The 49ers acquired Martin on Tuesday from the Miami Dolphins for a conditional seventh-round pick in 2015. The 49ers will only give up the draft pick if Martin makes the 49ers' opening-day 53-man roster.