This all comes down to the type of offense and defense that George Karl wants to run, just having skilled players doesn't mean they fit. Certain players will excel in one style and then completely flop in another style, that's why statistics only tell part of the story.
Now if are in fact going to run a type of Dribble Drive Offense then I would be leery of trading McLemore because of his speed, athleticism, and growth in shooting the 3-point shot. Understand that this offense is not dependent on the players being overall good ball handlers, it is more like having the burst drive ability, keeping it under control in quick and singular movements. Not a lot of improvising has to occur in terms of the ball handling, just the scoring and passing. McLemore can do this and do it well, we just haven't had the chance to see it much under the last couple of coaches we've had, if anyone can put him in the best place to succeed it is Karl.
Now I think Afflalo can excel in this offense as well, but there are concerns. He has a larger contract if he decides to stay and he also the choice to opt out, both of which are problems. Also his play has dropped significantly this year, is it a fluke? Is it the new coach and new offense? Probably, but who really knows. My point being is that it's not like Afflalo is a completely known quality while McLemore isn't, there are questions about both. If we lost them both in the offseason that would be truly devastating.
Finally with Dragic, we won't be trading for him, don't have the assets so it comes down to signing him in the offseason. I think he could do well in this offense too, but the problem is it sounds like he wants to be the man. He got a taste of it last year when Bledsoe got hurt and now that he's healthy along with adding Thomas and Green he is far away from the good times and that's why he won't be coming back. The thing is when he talks about being like Curry what he's saying is that he wants the ball all of the time. Curry isn't truly a point guard, he is the superstar, that's why he always has the ball. Curry has the skills to be that superstar, does Dragic? Also he needs an offense that allows him to try, do we have that? I remember last year we had Thomas, a player who also always wanted the ball and wanted to be a superstar, that didn't seem to work so well. Now I do think that Dragic is much more talented than Thomas, but with Cousins and Gay here I don't think that type of player will really fit.