Mike Yastrzemski homered among his three hits, and the San Francisco Giants survived a wild outing by starter Blake Snell to beat the Seattle Mariners 4-3 on Saturday. Snell walked five batters in the second inning, two with the bases loaded, and issued a season-worst six walks overall. Spencer Bivens (3-1) worked three efficient innings of scoreless relief, and the fifth Giants pitcher, Ryan Walker, handled the ninth for his third save.