The rotation that I root for needs balance. Enough ball handling, scoring, shooting, defense, size and rebounding. That's not an easy task with this Celtics roster. The best players are almost all guards and wings. There's enough scoring and rebounding can be adressed with the centers. But defense is an issue and especially, since the temptation is there to play too small, which we should absolutely avoid.
After some puzzling I found this to be the best starting unit:
PG: Kemba Walker
SG: Jaylen Brown
SF: Jayson Tatum
PF: Grant Williams
C: Vincent Poirier
Three legit scoring options (Walker, Brown, Tatum) adding more and we'd have the same problem as this year: not enough shots to get everybody in a rhytm. Walker and G.Williams are undersized, but overall it's okay. Poirier should be an excellent rebounder and a fine rim protector (theoretically I'd prefer Robert Williams, but unfortunately I think he needs some games in the G-league to grow). We don't have a clear starting PF, so hopefully Grant Williams can hold his own by using his BBIQ to do the little things.
So I start neither Hayward nor Kanter, since I think their offensive contributions are somewhat diminishing returns and our shaky defense will be putrid for sure with both of them as our front court. That doesn't mean that they don't have a big role on the team. Walker, Brown and Smart can play most (or all) minutes at the guards spots, so when Smart comes in one of them stays in. Hayward can be the other playmaker and make sure we don't have to rely on the shooting of Smart or other guys who feel they need to take responsibility.
I think Theis and Kanter can complement each other very well. The well-rounded game of Theis with the rebounding/post-game of Kanter. Nice duo to deliver a new vibe to the game. Just like the first unit, the second unit has 4 capable three-point shooters. This unit should really be able to make a difference:
PG: Marcus Smart
SG: Kemba Walker/Jaylen Brown
SF: Gordon Hayward
PF: Daniel Theis
C: Enes Kanter
So basically a 9-man rotation. Weaknesses are defense (when necessary bring in Ojeleye) and to a lesser extent playmaking (Wanamaker is decent). I would only bring those 11 players to the game, unless injuries, and let Edwards, Langford, Yabusele, R.Williams (and Waters and Fall) gain experience in Maine. Unfortunately I have to admit that they're not ready.
Overall rotation:
PG: Walker (32), Smart (12), Wanamaker (4)
SG: Brown (32), Smart (16)
SF: Tatum (32), Hayward (16)
PF: G.Williams (16), Theis (12), Hayward (12), Ojeleye (8.)
C: Poirier (16), Kanter (24), Theis (8.)
Total estimated minutes per game (big increase for Brown):
Kemba Walker 32
Jaylen Brown 32
Jayson Tatum 32
Gordon Hayward 28
Marcus Smart 28
Enes Kanter 24
Daniel Theis 20
Grant Williams 16
Vincent Poirier 16
Semi Ojeleye 8
Brad Wanamaker 4