The Denver Broncos know what their starting offensive line will be and which players will comprise it, but they’re working on determining their depth. On Friday, the first official day of training camp, the Broncos gained some deeper insight into one of their backups, as starting right tackle Mike McGlinchey was not in attendance at practice. Friday marked the second straight practice McGlinchey has missed, and afterward, head coach Sean Payton addressed the starter’s absence. “He should be returning, I’m going to say, either tomorrow or Monday,” Payton said.