It could be:
Mayo was told he'd have a full year to get comfortable.
Mayo was told he could ride the plan of keeping Maye benched and learning for the year while using a backup in his stead.
Mayo was told that he'd be guaranteed a second year to prove himself.
And none of those things came true when improvement wasn't happening. Or, more accurately, regression was the trend.
There's not much else to be led on about. He was part of a plan that isolated Belichick in the last year, and he knew it was coming. Which is whatever, if you're confident, do you and prove the haters wrong.
His team regressed (not just didn't improve, but regressed).
Eh. The only "truths" would be some meddling by the Kraft's in forcing Mayo's hand on things earlier than promised, and maybe throwing the last game. Not sure it'd do much to clear the overwhelming truths of suck this season :/