Every summer for the past three years, Steve Kerr has left part of his heart in the Bay Area and come down here to the place he and wife, Margot, call home. The Golden State Warriors’ head man loves Northern California, but he is a son of the sun, a beach boy at heart. Kerr is a serious coach — he has a pile of busted clipboards to prove it. But he’s also the guy who can laugh in the heat of battle, who will put a friendly hand on the shoulder of a ref, who demands that his players have fun. His personal vibe is in tune with San Diego, where people are serious about kicking back. Kerr strolls into a restaurant that is a stone’s skip from the beach. He is wearing flip-flops, his feet and ankles are caked with sand. He is cleverly disguised as a surfer dude in a Cubs cap. Not that he needs a disguise. It amuses Kerr that while he is known all over the world as the coach of the planet’s greatest basketball team, his fame hasn’t yet reached San Diego. When people here recognize Kerr, invariably they are tourists from the Bay Area. At the restaurant’s reception desk, I ask the hostess if Steve Kerr has reserved a table. She smiles and says, “I don’t know him.” Kerr laughs when he is told that. “There you go,” he says. “I rest my case.” Kerr doesn’t seek the spotlight, especially not in the offseason. He agreed to this exclusive interview because he recognizes the incredible interest the Warriors have created. And he knows there is great curiosity about his health. Over lunch, Kerr — as always — is at ease and willing to take on just about any subject, from yoga to politics. The good news: Kerr can still laugh. The laugh is important. It is a vital piece of his personality, it punctuates his speech and puts people around him at ease. For the past two years he has experienced chronic headaches in the wake of back surgery, and he laughs less often. But it’s still there.