Because there has been a lot of hand-wringing and some debate about the defense rushing 3 (or 4), or rushing 3 with a linebacker in the mix, I went back and watched the entire game again. I looked only at BYU's defense to see what the defensive line was doing.  Interesting things to note:

1.  Tooley (#31) was used the most as both a spy and a 4th rusher for most of the first 3 quarters of the game.  Wilgar (#49) had 14 of the 43 plays as the extra/spy (33%).  This leaves Tooley with 66% of the linebacker assisted rushing or spy plays.  He made a few mistakes letting the QB get around him or taking a bad line, but he also made some terrific plays (shedding the block of #76 for a TFL is a good example — which led to #76 getting ticked off and he got a personal foul for pile-driving Tooley on the very next play).

2.  Many times Tooley (or Wilgar) would kind of half-rush.  They would occupy the LT or RT (they only lined up on the edges) and allow the 3 actual D linemen to deal with the remaining 4.  This half-rush means they would stay at the LOS and just watch the QB and spy on him while being engaged with the O lineman.  This wasn't exclusive as sometimes they did rush.  Typically when this happened, the tackle would handle them for enough time to allow the QB to scan the field and throw a pass.

3.  Houston only had a single drive in the 3rd quarter.  18 plays long.  Started with 9:53 on the clock.  Ended with 3:05 on the clock.  Udo should have had the sack on the touchdown play, but the QB made a great fake away from Udo, and then juked Tooley at about the LOS and dove into the endzone.  Tooley and Wilgar split the plays 50/50 where they lined up as the 4th man on the line for this long drive.

4.  The majority of the rush 4 configuration was done in the 4th quarter as can be noticed by the "21" number there and no rush 3 or rush 3+LB numbers in that quarter.  At no time did BYU line up with 3 linemen and bring a linebacker up to the line in the 4th quarter.  It was always 4 linemen, exclusively (run play, pass play, whatever).  The two rush 4 configurations in the 2nd quarter were first where Batty had an offsides called on him (he was running around trying to figure out where to lineup ... Wilgar was on the line pointing him to the other side and Houston went from their 49 to BYU's 27 on that "free" play).  The other 4 man rush was from BYU's 5 yard line where they passed for a TD (so, kind of a standard goal-line look with 4 linemen there).

5.  Defense got burned during the first drive with a 3 man front, Wilgar on the line (rushing) and I. Kaufusi blitzing from his middle position (up the middle).  QB did a play-action pass across the middle to the TE for 30 yards (right where Kaufusi would have been had his drop been deep enough).  I wonder if this successful play by Houston influenced the defensive calls going forward.  They ran this same play 3 times.  1st quarter:  30 yard gain.  2nd quarter: 23 yard gain (again when BYU decided to blitz with Udo and Warner on the line along with Tooley) — what are the chances?.  3rd quarter:  They got sacked on this play — again, when BYU blitzed with Tooley on the line, and Kaufusi — this time on the same side of the line as Tooley (not up the middle as in the 1st quarter).  Only took 3 times to stop that play call.

6.  The 4th quarter was the best quarter for the defense and worst for Houston's offense.  5 times they had the ball in the quarter.  2 three-and-outs (-7 yards total between those drives).  5 play drive for 2 yards total.  6 play drive for 12 yards total.  Last drive was 3 running plays for 2 yards and they let the clock run out for the end of the game.  Total yards for Houston offense in the 4th quarter:  9.  9!! with 24 plays.  Wow.  In the 3rd quarter they ran 18 plays and gained 98 yards (that was the long drive) - not counting the 2pt conversion.

7.  If this game is an indication of how the defense works, then rushing 4 was certainly a better option than 3 or 3 + LB.  The good thing about this is that BYU knows how to do this type of defense; they showed it in the game.  Just need to do it now.

8.  93 plays from Houston (not counting punts or field goals).  10% (actually 9.6%) of the plays were a blitz by the BYU defense.  I haven't run the numbers from the other games, but I would assume this is fairly close to the others (I don't remember a lot of blitzing in those games).  All this means is that the defensive philosophy is conservative (they don't want to get burned ... see description above with the play-action pass for 30 yards during a LB blitz).

9.  I'm not sure the 4 man rush led to Houston laying an egg in the 4th quarter or for their QB to just miss open receivers, receivers to drop the ball (looking at you #22), etc.  However, that is the one changes that we can point our fingers at that does seem to show demonstrable results.  I wonder if they got so used to the 3 man rush (plus Tooley or Wilgar) that they hadn't figured out how to handle the 4th lineman (#57 Tofa played the most snaps but #44 Fevaleaki was in for a few plays as well — both actual lineman).

10.  My opinion is that there needs to be more changes with the alignments on the defense (especially concerning the line).  The bodies are there to run a 4 man front.  We definitely know how to run a 3 man front or a 3 man front with a linebacker.  I think we should mix it up more and not be predictable (see 3rd quarter drive ... which was terrible for predictability along the line).

The key below:

Rush 3: 3 defensive linemen (no linebackers on the line — just the 3).

Rush 3 + LB:  3 defensive linemen, plus the addition of a lineback on the line that rushes or eats up a tackle leaving 4 O lineman

Rush 4: 4 defensive linemen

                Q1   Q2   Q3   Q4    Total
Rush 3      :    7   10    1    0     18
Rush 3 + LB :   13   13   17    0     43
Rush 4      :    0    2    0   21     23
Blitz       :    2    2    4    1      9