2nd-year pro Martin's performance at left tackle will be big factor in Dolphins' season

Jonathan Martin has added 15 pounds to his already imposing frame, and the Miami Dolphins hope the extra weight will help the second-year pro anchor their offensive line for years to come.

Martin's expected to start this season at left tackle, where he's replacing departed Pro Bowler Jake Long. The 6-foot-5 Martin now tips the scale at 320, which means that if he fails at his new position, he'll be a big bust in more ways than one.

Aside from quarterback Ryan Tannehill, Martin might have the most impact of any player on the Dolphins' season. If he does a solid job, their offense could be significantly improved this season, with more big-play potential at the skill positions and a more experienced QB.