In response to Mployee8's comment:
Red had no intention of breaking up the Big Three ... the was part of the Celtics mystique and the Celtic Family thing ... they took care of guys that were champions. None of them would be traded under Red ... Period!!!
It seems to me also that under Gavitt (CEO) and Jan Volk (GM), the ownership was transferred from Dan Gaston to his son Paul (1993) who began prepping the team to be sold if my memory is correct. They were told not to sign any big contracts and to get the team salary down so the new owners could do their own thing. With "Thanks Dad" running the show and as much sucked out of the organization as possible by then (Media outfits acquired, stock sold etc) there was not big backer to fuel any rebuild. Gavitt knew the Big East and USA Basketball and had some insight to the new crop of kids coming up but depended on Volk for day to day ops. It took Paul about 10 years before they finally found the current ownership to take over ...
It was Red's 1960's philosophy that doomed the team at the start of the 1990's and the trade deadline of 1989 was what proved it. What Gavitt was unable to do with a worthless McHale and 39 year old Parish by 1992 is NOTHING compared to how badly Red set the team back in 1989.
Danny knew it. He told Red himself.
That is why healthy 30 year old Danny Ainge who was not quite retired # material found himself a 50 cent piece traded for two quarters instead of McHale, a $1.00 that everyone in the Celtics organization knew was going to be worth $0.50 in 1-2 years and $0.25 in 3, wasn't traded for two 50 cent pieces everyone in the NBA knew would be worth $0.75 in the next 1-2 years and probably be worth that amount for the 5-6 seasons after as well, long after McHale had fallen to pieces and retired.