I don't think Pierce will be playing 36-38 minutes. As a matter of fact, I won't be surprised to see the team try to hold both him and Garnett to ~28 mpg. This leaves a massive 40 mpg to be filled by backups, plenty of space to fit both Sullinger and Green.
Small lineups or not, though, I don't see Green ever being a viable primary backup for KG, and I see the remanining 10-12 mpg there as Sullinger's to lose at this point.
Not really...
Lets assume that Pierce, Bass and KG all start and play about 28 MPG.
That leaves 60 bench minutes to be split between SF, PF and C.
The biggest reason Doc loves Green so much they see him as the first genuine streth 3 since James Posey - their entire interest in him is the fact that he can play both forward positions. Consider that PLUS his 9M/year contract and I'd be willing to bet that Doc will want at least 25-28 minutes from Green shared between the two forward spots.
Not lets say Green plays only 25 minutes off the bench (20 at SF, 5 at PF) - that leaves 35 minutes remaining to split between PF and C, with possible candidates being Sullinger, Wilcox, Collins and Melo. I'd say that either Collins or Melo will probably get ~5 mins a game (much like Hollins last season) so that leaves 30 mins.
If healthy I would expect Wilcox to get pretty solid minutes at the PF/C positions mostly because he proved last year that he's capable of providing great energy off the bench. I see him getting 15-20 mins of playing time if he returns to last season's form.
That leaves 10-15 mins spare that I imagine would probably go to Sullinger, but all of this assumes that:
1. Bass only plays 28 minutes: He's only 26, so they may well play him 32-34 minutes which would bring Sullys mins down to 6 - 11
2. Green will only play 25 mins - Doc may want to give him more time and PF, so could play him as much as 30 MPG, and that would leave 1-6 minutes for Sully
3. That Collins and / or Melo play no more then 5 MPG combined. Due to his experience Doc may well play Collins as the primary backup centre (for 10-15 MPG), in which case Collins, Green and Wilcox would probably eat up almost all the minutes at PF and Center
Remember that Collins was the starting center for Atlanta at times last year, and has proven he can be effective (in terms of impact, if not statisitcally) in significant minutes. It's not unrealistic to think that Doc may give him solid minutes if he wants to maintain a big presence inside and protect KG from all that extra banging.
The depth and makeup of this Boston team - combined with their future direction - makes it very difficult to see how Doc will go with the lineups.
He may go with past history and give more minutes to the proven veterans (like Collins, Wilcox).
On the other hand he might see that time is running out for KG and Pierce, and may try to give significant minutes to Melo and Sully from the start to fast track their development.
Hell he may even start Jeff Green at PF, then slide him over to SF (and bring Bass off he bench at PF) when Pirce sits.
He may start Collins at Center and Garnett at PF so that KG can play his preferred PF position, then bring Wilcox (C) and Bass (PF) off the bench to back up those positions - very unlike scenario, but who knows?
If the past is anything to go by Doc will see who puts in the heart and the hustle in training camp and practice, and he'll reward those guys with minutes. Remeber that both More and Johnson got minute at times last year, and neither really showed even half the potition of what this season's rookies look to have.