Interesting thread, everyone.
I'll make one observation. Regardless of whether we're talking about bad teams like the 2006-2007 team or all-time great teams like the 2007-2008 team, high turnover #s have been a hallmark of the Doc Rivers era. If you want to look at a culprit, look at the offensive system implemented by Doc.
That said, I expect this year's team to be the best offensive team we've had in Doc's tenure. Doesn't mean we won't be among the worst teams in the league at keeping possession of the ball though...