I have trouble seeing how this roster can win more than 45 games. On paper, this team sucks... And it's only through the genius of Brad Stevens that we have a chance at sneaking into the playoffs again. The good news is, Ainge will be aggressive in the trade market this season and we still have some potentially valuable draft picks (like the Brooklyn picks which may end up late lotto).
No, it doesn't. I love Stevens. I love him a lot, but people have to stop with this hyperbole. The Celtics have some of the best collective defensive talent in the league on the wings (1, 2, and 3 positions), and they have one of the best go to scorers in the 4th quarter in the league. You are underrating the base talent on this team by a large extent. They won't win 45 games because Stevens is some genius. If they win 45 or more, they'll win it because they had both the coaching and talent to achieve it. They are going to grind out games (Smart, Bradley, Crowder, Amir defense will be hard to deal with for a lot of teams) and basically rely on players like IT to help close the game. No, they aren't amazing, but they don't suck on paper either.
Also, I always find it interesting to see you predict the absolute worst for the Celtics, but almost expect the best from other teams (BKN a late lotto team? if they are lucky). It's good to keep expectations low, but man, turn that frown upside down!

Last year, the Hawks -- a perennial 45-50 win, 1st or 2nd round playoff loser with no stand-out stars -- sent 4 players to the All-Star game, locked up the #1 seed in the East with 60 wins, and made it to the Conference Finals.
So, for the Celts to be that kind of surprise, what would it take?
For my money, the Celts would have to send at least one player to the All-Star game, overachieve by at least 10 wins in the regular season (so about 50 wins), and win a playoff series.
I know some people around here think all of those things could plausibly happen this year. Those people won't be surprised that I disagree. 
They need an Al Horford type talent to get there. We aren't getting that type of talent, though, and I have no idea when that will happen in particular. :/
For me, a surprise would be for them to maintain their 24-12 pace over the course of 82 games. That equates to roughly ~55 wins. I don't think they can do that over the course of a full season, and that would surprise. 50 wins may seem unlikely, but it wouldn't
surprise me.
I just don't think the Celtics are going to make the playoffs. They ended last year on a hot streak largely against mediocre/bad teams.
On average, every team in the East is
always playing against mediocre/bad teams. There's no sense in devaluing what the Celtics did because they had a weak close out schedule. Plenty of teams had similar schedules but did not perform at the level of the Celtics. The Celtics won't continue that blistering 55 win pace they had over the last 36 games (close to half the season!), but for them not to make the playoffs in the East, they would have to drop from a 55 win pace to a low 30-mid 30 win pace, which is just as unrealistic as expecting 55 wins. They are likely to fall in the middle of those two extremes which = playoffs in the East.