I think Fox is a better player than MPJ, but after this playoffs his value is probably going down at the point Spurs might have to give extra value in this trade.

On the other side MPJ is an NBA champion and fits well in SA, he also gives San Antonio cap flexibility towards Wemby extension as he’s in a expiring contract.

For the Nets assuming Fox’s contract ain’t a big problem as most of their payroll is rookie contracts, and Fox can upside Nets ceiling which is important with the new draft lottery.