There have been tons of 'great' scorers on bad teams, guys who can put up 20 to 30 a night regularly in losing efforts.  The players who do this and win generally, not always, but in the vast majority of cases, do something else for their team, like pass, rebound, defend.  Durant was a dominant player in college because he did more than just score.  He scored, but he was also among the nation's leaders in rebounding.  If he somehow decides that this is no longer part of his game and the Sonics allow this.  

"Taking" 5-7 rebounds a game  (in how many minutes?--this makes a big, big difference.  5 in 35 minutes, not very good.  7 in 30 would be pretty good) means accepting that a guy who was a fantastic college rebounder goes to strictly mediocre and loses one of those things that set him apart from the field.  Putting him at an off guard spot and not looking for rebounds from him would further mean removing an aspect of his game that made him valuable.  Green wasn't as good a rebounder, so why they'd want to put him in a position where he'd be in a better position to rebound than Durant seems strange.

I realize that scoring is what sets up highlight reels, what garners all-star votes, what gets big contracts, but the emphasis on scoring over all else is a mistake, and if he's a scoring off guard who doesn't rebound, expect him to get big paydays, big scoring numbers for 82 games until he watches the playoffs on TV.

I don't know that this is going to happen, but I do think that there are ways that Durant can be something other than a sure thing in terms of helping his team win.  One way would be if he doesn't rebound the ball and becomes a one-dimensional shooter.