One of the biggest problems that has plagued Lincoln Riley’s coaching career is having a stout defense. In the first half on Sunday with the USC Trojans facing the LSU Tigers, his defense made massive improvements. In the offseason, Riley brought in new defensive coordinator D’Anton Lynn, and the move seems to be paying dividends early against the Tigers. At halftime with the Trojans tied 10-10 with LSU, Riley spoke with Holly Rowe of ESPN and gave some credit to his much-improved defensive unit. “We’ve played gap sound. We’ve played very physical. We’ve tackled well in the open field. We’ve b…