In my opinion, market value is how much the market pays
This would mean that no player, ever, could be considered overpaid, right?
When I refer to the market, I mean what teams would be
willing to pay, not what they actually pay (only one team can sign a player at a certain time).
So, if everybody thinks this player is a $4mil/yr player, one team pays him $6mil and this player performs like a $4mil/yr player, then he's overpaid. If everybody think he's a $6mil/yr player, one team pays him $6mil/yr and he performs like a $6mil/yr player, then he's fair value. If every team is willing to pay $4mil/yr and one team pays him at $5mil/yr, but he performs like a $6mil/yr player, then this team appears pretty smart for paying a little extra to sign this guy in.
I'd say this is a case of everybody not willing to pay a high price on Jeff ($9mil/yr) except the Celtics (for many reasons: surgery, inconsistency, etc.) But if he continues to play at his current ability, then he's not really overpaid, he's almost a steal. Unfortunately, if his market price was $7mil/yr and we paid him $9mil/yr, we'd have been better off by paying him $8mil/yr because no one was going to outbid us, either way.
The question is, can he average the type of game a $9mil/yr player would make, over the next four years? Jury is still out.