For the Celtics: gets a playmaker, gives a protected pick, schroder and neismith and Langford as a young asset.
For the mavs: gives other weapon to run the offensive with the second unit, and a big vet that have some playmaker skills to help Luka. If everything goes bad, at least all of them are expiring, and for the offseason it helps for free up cap
For the spurs: gets cheaper young assets and a pick for an expiring contract and a good role player but have already reach his potential