Koppen was better than Andrews is. More stout in the middle in pass protection, and better in the run game.
That being said, he is a great story and someone who should be admired, despite his physical limitations. I'm really glad his hard work and determination is being rewarded financially.
I've been vocal on wanting Mangold as an upgrade, but its coming clear that he isn't healthy and STILL rehabbing an ankle that he hurt the end of last October, so he isn't actually a option for the foreseeable future so, like always, the Pats have moved on.
The Pats have a good OL, whose sum, (like the rest of the team) is better than the indivudual parts. They are getting the most of what they have, but won't get to be elite until they improve the center position, physically.
But until that day happens, Andrews isn't a liability