If St. Mary's goes 15-3 in conference they'll probably be top 40 in RPI.
Pomeroy and Sagarin both have them finishing 15-3 so it's not a stretch at all to think that they will. If Gonzaga goes 14-4 in conference then they should be in the top 50 as well and possibly the top 45. Again, both Pomeroy and Sagarin have them finishing 14-4 so that's not a stretch to think it will happen either. If BYU goes 15-3 then advancing to the CCG will most likely require beating either Saint Mary's or Gonzaga in the semifinals which would give BYU a 2nd win against a top 50 team.