I see it this way. Jordan has 2 years left on his contract. He won't help you win many games during the rebuilding period, so the job becomes to DEVELOP him as a player. He's only 24 - give him 2 years to reach his peak as a player, and then either let him go for cap space or keep an (improved) Jordan. Of course if someone wants to blow you away with an offer, you listen.
I don't think he's worth the money right now, but he's not badly overpaid by big man standards, is one of the most physically imposing players in the league, has only played for the Clippers, and is 24 years old.
Let's say he makes modest improvement to the point where he gives you 10/10/2 in 30 MPG, plays above average defense, loves playing for the Celtics, and shoots his usual 65%. Against a certain portion of teams he's extra valuable due to mismatch.
Sounds a lot like Perkins at his very best, which I would take (and not to be confused with washed-up Perkins)