San Marcos flag football outlasted Santa Ynez High in a defensive battle for a 13-6 win on Tuesday at Warkentin Stadium. The Royals’ and Pirates’ defenses took center stage in the opening half, exchanging stops and keeping the game knotted at 0-0 through three full quarters. Santa Ynez broke the tie on the first play of the fourth quarter with a rushing touchdown. A failed extra-point attempt left the lead at 6-0 for the visitors. San Marcos ans…