The Celtics won 50 games last year.
Pierce and Allen may now be past their peak, but I don't expect either to fall off a cliff. I don't expect Rondo to regress. So, let's say that, if as healthy as the past couple of seasons, there's not going to be that much difference in production from the trio between this and last.
We have a possibly rejuvenated Kevin Garnett and Shaquille O'Neal and Jermaine O'Neal in the front court vs. a recovering KG, Perkins, and Sheed. I'm not sure what the difference is there.
A full season of Nate Robinson with Doc's confidence vs a slumping Eddie House and Robinson working his way into the system should be an increase of at least a win.
Avery Bradley, Semih Erden, and Luke Harangody replacing Bill Walker, JR Giddens, and Lester Hudson as the young players to start the season? I see this as an improvement worth at least 2-3 wins. I foresee one of these players disproving the notion that Doc won't play rookies.
Marquis Daniels and Glen Davis had injury problems last season. I predict collective improvement between the two that is worth at least two wins.
Delonte West replaces Tony Allen. West is much more capable on offense, but TA has a legitimate claim to being in the conversation for the best defensive shooting guard in the NBA. It's hard to guess at what improvement, if any, there is. For now, I'll say this is a wash with a high standard deviation.
I'll also count the 15th roster spot vs Scalabrine as a neutral swap.
So, I'm predicting that the roster changes are worth at least 5 wins of improvement on a 50-win squad. Only the Cavs, Magic, and Lakers had more than 55 wins last season. Then, I'll add a couple more wins because I think the Celtics want it more this season and they won't seem as unlucky as last season.