Re: So... Wth are we going to do during offseason to make sure this won't happen again?
Nothing. You can't do anything to combat bad luck... Other than the pre-existing need for another ball-handler/creator, there's no point in making moves. Just wait for Rose/Deng to get surgery, heal up and hope that they come back strong for next year's playoffs.
If anything, try to flip Booz for something legit.
Oh and obviously try to get Dwight. That's a given though.