This is legal as two separate trades. The first is Klay for Wilson. The other is Martin for Williams. Mavs get out of the tax and create a huge TPE for Thompson, good for 12 months. The 2029 Lakers pick probably won't be in the lottery. In the likely event the Mavs miss the playoffs, this year's swap might prove valuable. I don't mind having Klay on the Nets next season, but the Martin contract is too long to take on without this year's swap.