Please correct me if I am wrong.

The Defensive Substitution rule says that a defense is allowed 10 seconds to make a substitution if the offense substitutes. BYU's substitution occurred with 15 seconds on the play clock. The flag was thrown when BYU attempted to hike with 2 seconds on the play clock.

Have a look: 3:36 on the game clock and 15 on the play clock.

When BYU subs with 15 on the play clock, all the Utah lineman look to the sideline to see if they are also subbing someone in. Clearly they are and all the Yewt lineman look away as if they did not see their sub jogging in. He takes the full 10 seconds to get to the pretending lineman. Then the swapped lineman begins his slow jog off the field. BYU hikes just before 1 second on play clock.

Am I mistaken, or shouldn't this be a penalty on Utah for too many men on the field. Is there a new rule that says they can take 15 seconds?