Here's my impression of TG's performance last year:
He lost faith in the team and the offense, and therefore lost focus and commitment. He was disinterested in grinding out a couple yards when he had no faith in the drive as a whole.
What would it mean to say this?
It would place a limit on his competitiveness. SJ ground out yards for bad offenses for years and never gave in. That is the competitive level of a great player. If I am right, then TG just isn't a great player. A team will not be able to count on him for the extra yard every time.
It would ALSO mean that his performance would be likely to rise again if we became motivated by belief. I see no reason to think that IF the team and the offense convince him to believe he won't recover his effectiveness.
I remember reading that the new coaching staff sees him as a pretty sharp student of the game. Sharp minds often (not always) get bored and disengaged. I think TG looked at the coaching staff last year and checked out mentally and competitively. And since his personality needs some engagement to perform, his performance really suffered.
If any of this is true--and whaddo I know?--then the things we hear about him being engaged in the coaching classroom could be pretty significant. If he goes all in, he may very well match his rookie performance level.
Of course, I am NOT making excuses. The player I describe is NOT a great player. But a not-great player can nevertheless be a very valuable and effective player if handled right.
Which is where coaching comes in. I suspect that McVay and Co. will be able to elicit production from him that a checking out Fisher no longer had the focus to draw out.
Just my sense of things.