Another way to look at it, the Celtics missed 57 shots, NOP missed 46 shots. We had 12 more ORebs. TOVs were 12 BOS vs. 10 NOP but they got 17 pts off turnovers, we got 4. We made up for that with 2nd chance points (23 to 10).
Another thing that stood out to me, Horford and Kornet together were +13 in 14 minutes, Horford and Porzingis together were -12 in 9 minutes. Last season, Porzingis seems to cause a spark every time he was on the floor. This season, very much the opposite. Almost every player had a worse +/- with Porzingis than without him in this game (the exception was Holiday who was +3 in 31 minutes with Porzingis). Another specific example is Tatum was -9 in 32 min with Porzingis and 0 in 4 minutes without him. These are awkward sample sizes so only go so far, but still telling I think.