I keep reading Celtics fans 'overvalue' Rondo but most of what I read here it seems as if he is undervalued. Look, noone knows what post-surgery Rondo will be like so all we judge him on is what he has done. That being said, this is a player who put up 18-18-18 in a playoff game, actually a little better.
Those numbers don't come around often, like maybe the last time was almost fifty years ago. You don't trade that player until you see what he is like after surgery. And, you certainly don't trade him for an unknown player even that player is in the lottery.
Rondo will come back from surgery and drive up his trade value by dominating games. Then when Ainge realizes that Rondo is not helping the 'tanking' effort he may then trade him.