Tanner's attention was focused on the deep sideline route, who was covered by the corner back. He still should have been sprinting to the end zone. Inexcusable to be jogging in the secondary when the ball is in the air downfield like that. But, because his focus was on someone else's assignment and he had essentially mailed in his coverage on that play, he completely misses the TE behind him.
I, too, think the USF QB was targeting the deep sideline route but the throw was too far inside. It took an exceptional and athletic catch by the TE to score the touchdown...but Tanner should have been right in the end zone to prevent that score.