The 24% calculation to make the tournament doesn't apply to every program. Many teams need to win 4 games to get the auto bid like most Pac 12, SEC and ACC programs. That lowers their chance to receive the auto bid to 6.25%. When combined with their at large chances, their overall chance to make the tournament is around 17.5%.

I concede that the average is 2 at large bids for NY6 games. So BYU and every other CFB program can claim one of the top 4 playoff spots and 2 at large bids. The other 6 spots are claimed by P5 conference affiliation and the auto bid for the G5 champ. So that is 4/128 + 2/122 which equals 4.8%. This wouldn't apply to everybody. Just Army and BYU.

So most years BYU has a 6% chance of getting to the Sweet 16 vs. a 4.8% chance for a NY6 berth.