Utah brought two, and #90 went wide because he saw the ball hit the ground. At that point, BYU's #75 was still thinking that BYU was going to pass, so he let #90 go wide and deep so that Heaps could step up in the pocket.
By that point, though, Heaps was already outside of the pocket - and by the way the defense was reacting, the OL could tell that something was wrong. They turned around to see what happened, and the rest is history.
If there had been a good snap (or Heaps hadn't tried to one-hand the bad one), he would have had plenty of space to step up and throw.