Luke Kornet is leaving Boston after signing a four-year, $41 million contract with the San Antonio Spurs. according to a league source.

The addition of Garza will soften the blow of losing Kornet, but Boston will need to do some work -- potentially a lot -- to shore up their big men.

The Celtics lost one of their key reserves in free agency as Luke Kornet is headed to the Spurs. Kornet agreed to a four-year, $41 million deal with San Antonio, a source confirmed to MassLive, as the big man got an expected big contract on the open market. ESPN’s Shams Charania was the first to report the deal.