It’s huge in every aspect of offensive football.
On the ground, you get back your best blocking tight end, so that improves the running game. He also could force defenses into more nickel packages which again, improves the running game.
In the passing game, you get back the best third-down and red zone threat in the NFL. Two areas the Pats have struggled most on offense this season. And not only can Gronk do damage when he’s catching the ball, just having him on the field will affect the coverage the Pats see. This will open things up a little more for the outside guys like Dobson and Thompkins.
Assuming he’s the same old Gronk (though I’m sure he’ll be a little rusty), you can’t understate how much of an impact he can and will have because he’s so good and so involved with every aspect of the offense.