Its a great trade for the Cavs. They are basically getting three players from Dion's trade, out of which two would definitely improve them in Shumpert and the big which they would get before the trade deadline. Dion is a very talented player and can be a good defender when he puts in the shift but that has been the problem. He has these mood swings which makes him a very unpredictable and frustrating player. When he is on his game, he will put up goo numbers in the offense and do a good job on defense like he did against Wade in the Christmas game. But then there are games like his last two games before he left where he jacks up shots from ridiculous angles and switches off many times on the defense.
I won't call Shumpert an elite premieter defender. He used to be a very good defender before he tore his ACL in 2012. Since then, he hasn't shown that kind of athleticism or the defense but in spite of all that, he is still a good defender and is a massive upgrade on anyone Cavs have currently except LeBron in terms of the defensive contribution.
As for JR Smith, well, bad case scenario, he will have the same output as Dion has been having till now by shooting around .40 from the field and scoring 10-12 points off the bench but if the Cavs can somehow sort him out and make him the player he was a couple of years ago, when he won the NBA Sixth Man Of The Year, they will getting a really good player coming off the bench to give them some bite. Also, I read this stat, that JR Smith was amongst the top five catch and shoot players in the league from beyond the arc. With LeBron there, he will get plenty of space to catch and shoot.
The first round pick from OKC which would be very important for them as well as they can used it to get a big rim-protector which they desperately need. They are rumoured to be pushing hard for Mozgov. I haven't wtached him play a lot but from the little I have seen, he seems much better than having TT there or even Andy this season who was quite underwhelming before his injury.
