I think it's foolish to try and guess what will happen as far as injuries and guys having up and down seasons.
What I feel confident saying at this point is that of the 15 teams in the East, only one of them for sure will not be in the playoff hunt, only a handful will definitely make the playoffs barring catastrophic injuries, and there are like 7-9 teams that could plausibly finish the season in any particular order.
The Celts are one of those 7-9 "might make the playoffs" teams. Anything from the 4th seed to finishing a few spots out of the playoffs is on the table.
We all have the right to our own opinions (after all, these are predictions so nobody is right or wrong yet) but I see it quite differently.
I think there are two teams in the East who have absolutely no hope of making the playoffs:
1. Philly
2. New York
I also think there are a number of teams who are very unlikely to make the playoffs, but if the basketball gods bless them and everything goes their way then they might have the tiniest outside chance:
1. Charlotte
2. Brooklyn
3. Orlando
4. Detroit
5. Indiana
Finally, I feel there are a few teams who are pretty much certain to make the playoffs:
1. Cleveland
2. Washington
3. Toronto
4. Milwaukee
5. Atlanta
That's 12 of the East's 15 teams accounted for, which leaves 3 remaining teams who, I believe, will (fairly) comfortably secure the other 4 playoff spots:
1. Chicago
2. Boston
4. Miami
The only other team I can really envision having much hope is maybe Indiana (based on Paul George's return and the addition of Monta Ellis) but I honestly think they are way too weak in terms of depth (after losing Hibbert, West and Stephenson over the past two seasons) to make much of an impact. Paul George might be a big star, but a big star can only take a really crappy team so far - just ask Kevin Love and Demarcus Cousins.
I know people will call me crazy for having Chicago and Miami on the 'battling for the final spots' list, but I have my reasons for this:
1) I think Jimmy Butler is the only sure thing in Chicago since Thibbs is gone, Gasol just turned 35, Noah declined in a huge way last year, and you never depend on Rose to actually suit up. They have survived up until now on their defense, which looks almost certain to fall apart after the decline of Noah and firing of Thibbs.
2) I think Miami is far too dependent on the Wade/Bosh duo
both remaining healthy though at least 75% of the season. Last season made it clear as day that Miami can't make the playoffs behind just Wade, or just Bosh. They need both of those guys on the court together if they want to make some real noise in the East, and last year they played around 100 games combined. I also don't believe that Miami is a good enough (at their strongest) to build enough of a lead in the standings to absorb the hit if they lose Wade / Bosh for significant time.
If anything I actually think Boston are the surest thing out of those three teams. They are a team that wins by sharing the load, rather then depending on any one / two guys to carry the team. This means that they if any of their players get hurt or go through a cold streak, they will pretty much always have another guy ready to step up and take his place. Where other teams will go through hot and cold streaks (as their key players go through injuries and/or streaks of their own), the Celtics should be able to remain consistently strong throughout the course of the year on the strength of their depth.
We will see.