Every team has a "token" 5th starter who is not a primary option on offense. And the Jazz have no SF's (if Hayward is indeed a SG). Marvin is a decent defender and can knock down the three. Unless the Jazz draft a stud SF, Williams would be a decent 20 min/per player. He starts and comes out early, then Hayward slides over to SF when Burks enters the game. Gordon/Alec get 35 mins each, Williams gets 20-25. Or have Marvin come off the bench if Hayward can be the starting SF. Just depends on who the Jazz draft or acquire in a trade. What I like about Marvin is he can also fill in at PF in case of injuries. For the right price, he'd be a good veteran to keep.
Well if the Jazz draft a SF with their lottery pick there is no reason to keep him.