I imagine Brown will have a good amount of opportunity coming off the bench to get some minutes. Remember, Stevens has said he doesn't use a traditional 1-5, but rather 4 positions: Ball Handler, Wing Man, Swing Man (guys who can play the 3 and small ball 4, for example), and Big Man. Brown is both a wing man and a swing man.
He should be able to play right off the bat as a defensive player off the bench, backing up anyone 1-4. I think if Brown is playing you just need someone else in the lineup that can handle the ball as that does not look like his strong point right now.
Imagine a small ball defensive lineup of Smart, Bradley, Brown, Crowder, and Mickey? I think Brown could pair well with a lot of our guys, as long as you don't rely on him as your primary ball handler.
As for Durant, I think you cross that bridge when you get to it. Brown should be versatile enough to fit into the puzzle somewhere.
Good, versatile pick from Ainge. I'm excited to see how he does!