First, I'd say that his lack of route-running skill means he needs more time to get ready, not less. If the guy could run decent routes already, he'd might not need much time.

I'm sure McVay has the ability to get more out of Tavon than Fischer did. When Tavon was productive, he was one of two offensive weapons, now he will be one of five. So the question is whether or not he will be worth taking someone else off of the field - or at least how often that makes sense. What flexibility to you gain or lose by swapping him for a TE for instance.

Looking forward, it comes down to his stupid salary. Even if he is productive, how much more productive will he be than the guy that comes off of the field when he goes on. And how much better is the team overall when his salary is used for a guy who might play 50% of the snaps vs. two guys that play 90%, say a good OG and a good LB, that play every down for the same total salary