I tbink its pretty obvious watching Geno operate in tbis offense and analyzing whats going on in Chicago (listening to expert commentary from guys like M Schlereth on Waldron) that Grubb isnt 'improving' Geno as much as he is maximizing what the guy is capable of. There's a difference between :
1. scripting a tailored playbook to a qb with a range of deficiencies and as an OC,
2. Putting as much as your qb can handle on his plate and using his knowledge of the game and his talents to break open the potential of an offensive unit.
Scenario one is dialing things back
Scenario two is turning things up.
Grubb and Geno are turning things up.
Geno and this offense under Waldron was like being handcuffed to a golfcart rolling downhill. Geno's play this year is the best evidence there is to prove that the good that we've seem from him the last two years wasnt an aberration. Watching the way he plays, his accuracy, his decision making... those thing are as evident now as they were last year. Grubb is just calling games that make sense, keeping his foot on the gas, and growing into what Geno does well - and thats a lot. I havent seen a throw the dude cant make. Im sure Grubb is elated knowing that he has a guy that allows him to run probably everything he can think up.