I'm a nostalgic pats fan, so I want to see our current players succeed and become all-pros, but realistically, we could drastically upgrade the 3 interior line positions...
As durable as Thuney was, he wasn't much above average. My ideal scenario would be if we could find a Mankins 2.0. Thuney would still be an amazing asset as a sixth lineman, presumably backing up all 5 positions.
A healthy Mangold is absolutely an upgrade over Andrews. Mind you, I WANT Andrews to be the best fit, but fact is, we were somewhat weak on the inside even WITH scar back. Giving Scar a pro bowl center would be like giving TB Randy Moss.... Good things would happen.
The one of the 3 that I would keep is Shaq. I believe if he has a pro bowl center next to him, he can really be free be a RG. We've seen him get beat badly one on one, but if he can do more helping and pulling, he's a dangerous weapon.