So Pritchard gets a contract and comes out and plays well in two preseason games, good for him. We have some saying that it is an overpay for a back up (who would have thought from the cheap owners), some saying it is about right, some saying it is about having a trade asset down the road.
I see the simple answer as the most likely. Boston likes Pritchard, believe he can help the team, and was able to sign him to what to me is a pretty team friendly deal. And whether or not he is part of a trade at some point in the future, a player on a good contract has higher market value than a player on a bad contract. This is not a contract that would ever need to be "dumped". It is a good contract for a useful player.
I don't think this contract is about trading Pritchard, in fact now he has a poison pill attached to him. In his case, the values involved are not that major, but this extension makes it harder to trade him. I think this deal from the Celtics perspective is about keeping a useful player on the team.
Poison Pill
Payton Pritchard is on a rookie contract and signed an extension that is to begin the following season. Therefore, he has what is known as a "poison pill" contract. He can no longer be traded for a player making equal money. Instead, his current salary is averaged along with the salaries he is to receive in his extension, and that average becomes his incoming salary for trade purposes. His outgoing value for the Celtics will be $4.0M while his incoming value for the receiving team will be $6.8M.