BYUs defense this year has put up great numbers in the 4th quarter. BSU possessed the ball for just under 7 minutes in the 4th including final snaps taking a knee. They punted twice and scored 2 field goals in the entire second half.
Here is the rest of the 4th quarter drives from opponents.
USU 1 punt, 1 INT, 1 TD
USF 1 TD
ASU 1 Fumble, ran out of time on the final possession.
Utah 1 field goal 1 TD 1 turnover on downs
AZ - 1 missed FG (following a huge sack) 1 INT, 1 made field goal.
In every single game except for USF and BSU the defense has forced a 4th quarter turnover. Your assertions are completely false.