No.
The trade would basically be Amir + Marcus for Millsap. The Celtics get better in the short term, but basically give up a chance to go after a big name FA in the offseason (other than extending Millsap).
Who is the big name free agent though? There are three all star level free agents available this summer (assuming Durant and Curry both re-sign in GS). Hayward, Griffin, and Millsap. That is it. If Millsap is at worst the 3rd best free agent available then why wouldn't you just acquire him now and significantly increase your chances of retaining him in the summer.
If Ainge starts getting emotional like you want him to be, then he will end up making a mistake. Unfortunately, this isn't baseball. If you make a mistake in basketball, it screws up your team for the long haul. Milsap is old. He is going to be a free agent. The Celtics need a Center. Milsap will get demolished by the Cavs and we lose Smart who can guard LBJ and Irving while being the 2nd playmaker on this team. He is also 22 years old.
We're not the New York Knicks. We don't just make trades for the sake of making trades so our team can improve a little bit and lose in the playoffs once again.
Again, thank god Ainge is GM because at this point, you would have us be irrelevant for the next 20 years.
Actually the emotional move is hanging onto a backup guard that is one of the worst players in NBA history because you have watched him play for 2.5 years and drafted him. That is the emotional move. Horford would play center with Millsap at power forward. Big and clear upgrade. Any time you can add what would be your best player for some bench players and limited future assets (like say Boston's 2018 1st) then you have to do it.
And no I don't think Millsap makes Boston a real contender, but he certainly makes Boston a heck of a lot closer than they are now and with an injury to James, Boston would be the best team in the East with Horford, Millsap, Crowder, Bradley, Thomas as the starting 5 and Johnson, KO, Brown, and Rozier on the bench for a very nice 9 man rotation. I think the Cavs even without James would still beat Boston as currently constructed and Toronto most definitely would. Millsap alters that picture a great deal.
He's not the best player on the Celtics lol. You clearly overate Milsap who hasn't been able to shoot threes well this season, nor did he last season. He is on the decline. That is just a fact. It's embarassing that you think he is better than Thomas at this point as well. Also, HORFORD IS NOT AS EFFECTIVE AS A CENTER. Have you not seen that this year? Is that midget Milsap even going to solve our rebounding problems. So he can't spread the floor like he used too, he doesn't do a great job reboudning, but yet he is making us close to a contender? Do you not factor in guard defense? Have you even watched the Celtics play recently? I'm a big Smart basher, but he is actually a very useful player. It's like saying Tony Allen has no value. Over time it's been proven he clearly does.
But yeah, keep claiming Milsap would be our best player. Can't wait for Smart to shut that midget down again in the playoffs.
And if the James scenario holds true, which is a pathetic scenario. Shows how desperate some people are to win now. You are not accounting the team from the West? Draymond Green would eat Milsap alive. But let's ignore that as well. I mean who needs Smart's defense against gifted guards our league currently has. Let's get a old midget.
Smart comes off the bench for a reason i.e. he isn't as good as Thomas or Bradley. He is an excellent defender, but he isn't as good a defender as Bradley or probably Crowder. Couple that with his terrible shooting, high turnover tendency, and poor decision making and he will never be anything more than a role player. Millsap is not a role player. Millsap would be Boston's best player (Thomas is a much better offensive player, but the gap defensively is far greater). He is a + player in all facets of the game. Solid defender, solid overall offensive player, good passer, rebounder, shot blocker, steal generator, etc. And yeah he is on the wrong side of 30, but so is Horford. Boston didn't sign Horford to build around the Brooklyn picks, it signed Horford to try and win now, and while Millsap alone doesn't make Boston a real threat to the Cavs or Warriors, it brings Boston a lot closer and should at least put Boston in the ECF to play the Cavs.
If Boston were to acquire Millsap for Smart, Jerekbo, and Zeller (and maybe a future non prime pick like say Boston's 2018 1st lotto protected), Boston would significantly improve its team and would be one move away from a real title contender.
Post-Trade Boston would be (with 2 open roster spots to add vets or whatever)
PG - Thomas, Rozier, Jackson
SG - Bradley, Green
SF - Crowder, Brown, Young
PF - Millsap, Olynyk, Mickey
C - Horford, Johnson
That team is clearly the 2nd best team in the East something Boston isn't now. That team would have a very strong 9 deep playoff rotation (starters + Rozier, Brown, KO, Amir). Is it good as Cleveland, no, but it certainly is a lot closer than the current team.
And for the record, Millsap went for 17/10/3/1.5/2 against Cleveland in the playoffs last year. His shooting was poor, but he still filled up the stat sheet. He shot a little better against Boston than he did against Cleveland, but had lesser stats on the whole. Millsap was also better last year against Cleveland than he was the year before. So yeah he is a bit older, but he is still performing well and would fill a huge need on the team.