SAN DIEGO (AP) — Fernando Tatis Jr. homered twice, including a 447-foot grand slam, and drove in six runs for the San Diego Padres, who beat the Seattle Mariners 9-2 to sweep a nine-game homestand. The 22-year-old superstar sent Petco Park into a frenzy on a sunny afternoon when he drove a 1-0 pitch from Robert Dugger to the base of the batter’s eye in straightaway center field with one out in the seventh. Knowing it was gone, Tatis took a few steps and, holding his bat by the barrel, flipped it aside before starting his trot.