I don 't know the exact sequence here, but Ainge sure came out of this smelling like a rose. Irving just about fell into his lap. I don't think he was ready to entrust the PG position to any 19yo kid--not for this team aiming to challenge the Warriors. As for IT's agent, it is customary for agents to look for the best deal for their clients--and for their highest commissions.
I'm sure IT felt underpaid, considering his huge impact on the Celtics. I still hearken back to Zeller's contract-- a scrub who was paid more than IT and other bigger contributors. I'm sure that was a bitter pill to swallow for IT. He now wants to get paid.