Since the PB value would have to be set at some point in time, I'd set it the start of games after the trade deadline passes. This represents the team that goes into the offseason, before it can be manipulated.

Playoff teams adding players would hurt themselves in the FA draft order - but that's true in real life when contending teams take on salary, often contracts that are too expensive. Teams that trade away at the deadline help themselves for next year (if they keep winning - if the trades make them lose they might drop draft position) as they created salary space just like real life as well.

You could also set it after the rookie draft and teams cut down. That would be more bold - teams might decide to make some higher PB rated players available that they aren't planning on using that much.

Fred Cline