The projection of offensive linemen from college to the NFL is a very difficult process. The athleticism required as an offensive tackle in college is far below the necessary ability in the NFL; it's why so many tackle don't pan out, and it's why certain players move to the inside.
Of course, this means that any ranking of interior linemen will come with a major question mark due to insufficient film. It's educated guess work.
The Patriots know their interior line needs a lot of help as left guard Dan Connolly is a free agent and right guard Ryan Wendell is far from a roster lock. New England sent former coach Dante Scarnecchia to the NFL Combine to help look at the prospects.
With all of this in mind, here are my interior line rankings for the 2015 NFL Draft.
1. Iowa's Brandon Scherff, 6'5, 320 lbs. Scherff is an extremely polished left tackle who projects to be a dominant offensive guard. A team could absolutely draft and play him at tackle and have positive results, but he projects to be an even better guard than tackle. His technique is fantastic, while his ability to recover in a short area makes him a top interior prospect. He's likely a top 10 pick, however, and is out of the Patriots price range.
2. Florida State's Cameron Erving, 6'5, 310 lbs. Erving is a former tackle converted to center, with the size, intelligence, and athleticism to play any spot on the offensive line. The Patriots have a connection with FSU's offensive line, as Bryan Stork was Erving's predecessor at center. Erving is expected to be a late-1st option and has the potential to be a star.
3. Pittsburgh's T.J. Clemmings, 6'5, 310 lbs. Clemmings is a converted defensive end so his technique is still extremely raw. That said, if the Patriots were interested in converting Cameron Fleming to a potential right guard, Clemmings blows Fleming out of the water. Clemmings is an All American right tackle, in just his second season on offense, who shows skill as a pull blocker who can stay on his feet. He's a mid-1st option due to his potential, with a possibility to fall into the 20s.
4. South Carolina's A.J. Cann, 6'3, 310 lbs. Cann is the top ranked pure guard and he deserves the title. He's a great player who flashes athleticism and polish. He lacks the same upside as the prior three, but he's a starter out of the gate and has the tools to be a long time starter. He's likely a late-1st, early-2nd option.
5. Duke's Laken Tomlinson, 6'3, 325 lbs. Tomlinson is a long time starter at right guard and offers tremendous size; think Marcus Cannon, but with proven experience on the inside. He's been impressing everyone during the offseason process and is the favorite of plenty of analysts. He's a mid-2nd choice.
6. Florida State's Tre Jackson, 6'4, 325 lbs. Jackson had an awful game against Oregon in the college playoffs, but he presents starting traits at right guard. He's big, he's strong, and he's stout. He lacks the quickness and recovery ability of other prospects, but he's similar to Tomlinson at a slightly cheaper price as a late-2nd choice.
7. Texas A&M's Cedric Ogbuehi, 6'5, 300 lbs. Ogbuehi is an interesting prospect as he was an elite prospect at tackle, who tore his ACL and fell down the board. He had been highly regarded as a right tackle, before flipping to the left side early on and struggling. He's a former highly touted guard, though, so moving him back inside makes sense. With the injury discount as an option in the 3rd-4th round, he might be too good to pass over.
8. Louisville's John Miller, 6'3, 315 lbs. Miller is another long time starter at guard who has the makings of a consistent contributor in the NFL. He doesn't really "wow" in any facet, but he's a plug-and-play prospect and a larger version of Ryan Wendell likely available in the 3rd-4th round.