I wouldn't call Meyhew a good GM. He was terrible with cap space and constantly missed on later round draft picks. That being said, he hit on enough picks to make a difference between being ok and being terrible - the issue is we didn't hit enough to built DEPTH. Of course his biggest fault is the pick he did not make: Aaron Donald. He might still be GM, and Caldwell still the coach, if he had made that obvious pick instead of reaching on Eric Ebron.
One thing Quinn was really really good at was managing cap space. Of course though, it's easy to manage cap space when you spend most of your time cycling in/out mediocre-to-below average roll players at the bottom of the roster. Being good at managing cap space also frees up a lot of money you can waste...which is what he did by over paying a bunch of Patriots castoffs over the years. So even the one thing he was good at turned out to not be a good thing in the long run.