If you went back in time to when each signed on with BC, few would have predicted that Anthony Castonzo would be a first round left tackle while Rich Lapham was hoping to be a late round pick. The heavily hyped Lapham was a three-year starter but never earned any conference honors. He played an important position (RT) but faced injuries and inconsistency. Many of his linemates over the last few years were better college OLineman, but they weren't 6'8 and 315 lbs.
Size is a big reason Lapham will get a second look. He has trouble blocking faster players, but still moves well given his frame and weight. On paper he looks like an NFL lineman.
I never particularly cared for Lapham's play on my second viewings. He was above average in the run game, but not great in pass protection. He seemed to make a mistake or two throughout. His length never seemed to be an asset, but he showed good strength on power moves. Also -- and in a way most damning -- when he went down, I thought his replacement (Cleary) played better.
The good news for him, outside of his size, is that he truly did work in multiple systems. Unlike Castonzo or Claiborne, Lapham did spend time playing OL under TOB. He then slimmed down under Jags for the zone. Then he moved to our mixed scheme under Tranq. His ability to adapt is a good sign. It means he's coachable.
As far as downsides, I don't know if Lapham can play anything aside from Tackle. I also don't know if he has the balance and speed to handle Left Tackle in the NFL.
I don't expect Lapham to get drafted. But I do think he will have multiple teams interested in tryouts and free agent deals.