Even Luke Walton didn't expect to become head coach of the Lakers this quickly. Walton met with Lakers executive vice president Jim Buss and general manager Mitch Kupchak on Thursday at Jack London Square. The Lakers offered him the job Friday and he soon accepted. By 4:00 p.m., he was calling Warriors head coach Steve Kerr to tell him he would be leaving after Golden State's postseason. Walton has deep ties to the Lakers - he spent eight-plus seasons with them as a player - and grew up in Southern California. Ron Kroichick is a San Francisco Chronicle staff writer.