I don't know. The arrival of Will Campbell, Morgan Moses, and Jared Wilson has drastically altered the offensive line compared to last year, so I would say that had Mayo had them, he would have been more successful.
However, to your point, Vrabel - in my opinion - will finish this season significantly better than Mayo would have with this same roster. At the same time, a lot of that has to do with his experience as a coach and knowing how to manage a roster and a staff. Mayo's biggest issue was ultimately his not being able to control keeping his thoughts to himself.
If you watch Vrabel, there are many times during a press conference where he'll stop and think about something before he says it, and that was the thing that really buried Mayo last year. But I also think Mayo and DeMarcus Covington were out of their depth on defense, and those two were outcoached last year more times than I can count.
Still, people probably could have lived with the record had it not been for a lot of the things he slipped up and said, where he painted himself into a corner and gave the radio too much to talk about, which they obviously listened to. And by the end, people were done with him, and based on the reports after the season, so were the players. There was also consistent regression, which I think had to do with player trust and morale, which is something Vrabel clearly understands.
I think more of Mayo's issues were less football-related in terms of why he was fired. But the difference in experience on this staff is also significantly different from a year ago. Maybe if he had a more experienced staff like Vrabel, a couple of those guys (McDaniels, Marrone, etc.) might have been able to save him from himself so he could mature and move past it, but the point is sort of moot now, anyway.
Guy was a good player, and it's unfortunate it worked out the way it did. I certainly wish him the best.