Good points all around.Has there been much discussion on the contracts here? That has to be considered. Crawford is at the end of a rookie deal, so it would help to include an estimation of what he would be resigned for, if at all. Otherwise he's a payroll dump, which isn't the end of the world.
Despite what some people say, Demar is not playing "excellent" basketball. If you look at his stats, he is about as close to being average at everything as you can find. In that sense he isn't really bad at anything, but certainly does not have any outstanding productive qualities. He is playing excellent basketball compared to his past seasons though, its just that the standard there is really low.
He is also one of the 10 highest paid SG's in the league, which considering the relative weakness of the position, makes his contract more expensive.
Based on the short season so far, with a Crawford trade, you would be getting a guy 9 months older, a slightly better scorer (although on a lower volume), more assists etc, with the major exception of a huge downside if he regresses. Credit to Demar, he seems to get a little better every year, which I think limits his downside risk. With a qualifying offer for JC of around $3m, I think you do the deal (if a mid 1st round pick is included) simply to get the remaining $35m for Demar off the books.