There is clearly a real use/need for him defensively. His ability to switch was one of the biggest reasons that we were able to make such a big comeback against the Bucks. It's an important skill that becomes even more important in the playoffs.
I don't think the answer is to replace Frye with TT on the 2nd unit. The unit definitely doesnt feel right offensively and they're not a defensive unit so you're not helping their strengths which is the problem with TT being in it.
I really think he should start with Bron, Love, IT and JR. Then he can play spot minutes in different "athlete" lineups with Bron or Wade in. Crowder is so versatile you can still get him his minutes throughout the rest of the game. Crowder and Green together usually produces well it seems.