I see three opponents we should lose to - OKC, San Antonio, and Houston.
We should beat Brooklyn twice and Philly once.
Call that 3-3.
The rest of the games are hard to predict. Atlanta, Milwaukee, Washington, Dallas, Indiana. Those are teams the Celts can beat but could easily get blown out, too.
Schedule skews toward home, though, so I'd guess that the Celts will win more than they lose. So 8 - 7 sounds right.