How does defense cause delay of game in college football?

Answer 1

Near the end of a close game where the defense is ahead and is trying to burn the clock, the officials will try to spot the ball as quickly as possible following a running play, before too much time runs off the game clock. Sometimes the defense will try to prevent the officials from spotting the ball quickly. The tacklers may refuse to get up off the ball carrier, or may "accidentally" flip or kick the ball away from the officials. Such actions can result in the defense being flagged for delay of game.

Answer 2

Yes, there can. There was defensive delay of game called against Oklahoma against Texas Tech last night. Exactly WHY is still being investigated.