I don't like Butler at the MLE. And it has nothing to do with his game or his injury. Adding Butler essentially negates the idea of playing Jeff Green anywhere else but at the 4, which is not his strong suit. Sure, I know we all like to say that Butler will be the "backup 2" and Green will be the "backup 3," but even if Doc cuts down on Ray and Paul's minutes, they'll both still play at least 30 mpg (and let's face it, probably more). If that's the case, it's going to be very tough to find either Green or Butler more than 20 mpg.
And to me, it seems silly to blow the whole MLE on Butler when we have such dire need of big men. I think we're a far better team bringing back West and Green (and letting them handle all the backup minutes at the 1-3) and then spending the MLE on the best big man that money can buy.
Butler is just too redundant with Green in terms of position (not game) to be enough of a net gain.