DAVIE, Fla. (AP) - Jonathan Martin weighed more than 300 pounds at the start of the year and decided to do something about it. So he undertook a rigorous workout routine - and gained 15 pounds.
For an NFL offensive tackle, pounds can be a plus, and Martin was pleased to add some heft.
``I think it will help a lot,'' he said, sweating in the sun after a Miami Dolphins training camp practice. ``It'll give me a better anchor and more power in the running game.''
The Dolphins hope Martin will anchor their line for years to come 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 second-year 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, because they have more big-play potential at the skill positions and a more experienced QB.
But if Martin can't consistently protect Tannehill's blind side, the Dolphins might be destined for a fifth consecutive losing season.
``I played left tackle in college, so I'm really comfortable there,'' said Martin, a second-round draft pick in 2012. ``I'm confident in what I can do. I'll just do the best I can to help this team win.''
Martin, who blocked for Andrew Luck at Stanford, started the first 12 games with the Dolphins last year as a rookie at right tackle, then moved to the left side when a triceps injury ended Long's season. Long, a mainstay in Miami since 2008, became a free agent and signed in March with the St. Louis Rams.
The Dolphins courted veteran Bryant McKinnie as a potential replacement, then decided to go with Martin on the left side. Their new right tackle is 6-foot-6, 330-pound Tyson Clabo, who spent the past seven seasons with the Atlanta Falcons and was a 2010 Pro Bowl selection.
Clabo will wear Long's No. 77.
``He's a very talented player, and from what I understand he was very well liked and a good locker-room guy,'' Clabo said. ``So obviously I'm not trying to replace him. I'm just trying to come in and find my own spot and fill the void that's my job to fill, provide a veteran presence and help this team figure out how to win.''
Better blocking would make the path to the playoffs easier. The Dolphins ranked 27th in the NFL in yards and 26th in offensive points in 2012, when breakdowns up front were a frequent problem.
Long's a former No. 1 overall draft pick, but a series of injuries took a toll on his performance in the past two seasons, and last year he allowed seven sacks in 12 games.
Martin gave up 8 3/4 sacks while allowing 47 quarterback hurries, the most in the league, and seemed mismatched at times at left tackle, where he often faced the opponents' best pass rusher.
``We saw a lot of progress. We saw development there,'' coach Joe Philbin said Wednesday. ``His technique was good. He needs to work on the consistency of his punch, but overall we thought he played well. He had the whole offseason to get comfortable and work on things, so we're expecting him to play better.''
There's no clear backup plan if Martin flops or gets hurt. Four days into camp, the backup left tackle is third-round draft pick Dallas Thomas, and Philbin conceded he's not comfortable with depth in the line.
``I don't know if I'm comfortable with the depth at any position yet,'' he said.
While the Dolphins have made changes at both starting tackle spots, the interior line personnel remains the same, with Mike Pouncey at center, and Richie Incognito and John Jerry at guard.
``It takes all five for us to be good, and we're going to be good,'' Pouncey said. ``We definitely miss Jake, but Jonathan Martin is adjusting to the left side, and we're looking for a big year out of him.''
Miami's season might hinge on it.
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