Despite Noel poor play , Philly will still think highly for him 
He's poor play more has to do with sharing the frontcourt with Okafor 
Their team is a mess 
And choosing 3 C highly with their draft picks makes matters worse 
They will probably trade Noel and embiid and keep Okafor as he is the safest bet so far 
Noel + stauskas + marshall   = Smart + Bradley + olynyk + Memphis 1st rounder 
This trade removes some of their front court logjam and improves their backcourt immediately 
By giving olynyk it provides spacing for Okafor and a young player with some potential 
Smart is a young player with potential. Didn't want to trade him but Judging by ainge willing to let smart go in a similar trade and drafting rozier, chances are he isn't that high on smart being the future PG. or sees Noel as being more value. 
Bradley is a good player and a vet that can help mentor the young players. Didn't want to trade him but Had to include at least 1 good vet for them as that is what they need. 
Memphis 1st rounder thrown in as they would expect at least 1 first rounder for Noel and I didn't want to trade a Brooklyn pick as well as them already having plenty of picks next year. 
Celtics gain Noel as a rim protector and player with potential 
This immediately fixes our front court and stabilises their playing time 
Fixes the logjam in the back court So we can play young, hunter and rozier more mins