If Avery Bradley (2013) was playing point and Avery Bradley (2015)/ Marcus Smart were playing defense against him, Avery Bradley (2013) would not be able to bring the ball up the court 3/4 times.
The 2013 Celtics would destroy the 2015 Celtics in the half-court, but they'd have to get there first.
Avery Bradley (SG, 2015) has the advantage over Avery Bradley (PG, 2013) both offensively and defensively. (++Advantage 2015)
Paul Pierce (2013) has a major advantage on offense against either Crowder or Smart, but I think the match up is closer defensively. (+Advantage 2013)
Jeff Green has the advantage over Evan Turner, both offensively and defensively, but I think this match-up is closer than any Jeff Green Fan (tm) would like to admit. (+Advantage 2013)
Brandon Bass (2015) is a major improvement over Brandon Bass (2013). He's the same athlete, only with more tools. (+Advantage 2015)
Kevin Garnett has the advantage over Tyler Zeller in both offense and defense. Garnett is strong enough down low to give Zeller fits, and he's quick enough to keep up with Zeller on the pick and pop/15 foot jumper game. (++Advantage 2013)
Coach wise, I'm giving it to Stevens by a hair. This could be a wash, but frankly, I think Stevens means more to the 2015 team than Doc meant to the 2013 team.
I think it comes down to the bench. If Jason Terry can match IT4 in production, the 2013 team wins. If IT4 out performs Jason Terry, which I think is probably the case more often than not...
2015 in 7 games. Smart and Bradley average 4 steals apiece.