This post assumes that Gonzaga finishes WCC play at 16-0.  

Right now BYU is currently in the driver's seat as they can control their own destiny.  If the Cougars finish 3-1 (loss at Gonzaga), they will beat out San Francisco and St Mary's by at least one game.  Wins by BYU in the next two games would guarantee the Cougars no worse than a 2nd place tie (assumes St Mary's losses to the Zags).  

If the Cougars lose on Saturday but win their home games, the Cougars will finish with 5 losses and would be tied with San Francisco and/or St Mary's unless one of them has an upset loss.  All three teams will have split with each other so the first tie-breaker will remain a tie.  The 2nd tie-breaker is having the best record against the top teams in the conference.  Everyone will have been swept by Gonzaga and so they would look at the 5th place team next.  At this point there are 4 teams seperated by 1/2 game for 5th - 8th place.  The odd scheduling this year could very well play a huge factor in the tie-breakers this year (for example, what if LMU finishes 5th and BYU was 1-1 against them but USF and St Mary's were both 1-0).  The tie-breakers makes the LMU game on Saturday extra big.  

USF's (currently at 4 losses) remaining games are at Portland, at BYU (must win game for BYU), at Santa Clara, USD, and LMU.  For tie-breaking purposes the Dons lost to USD and only play Pacific and LMU once (two teams very much in contention for 5th place).

St Mary's (currently at 4 losses) remaining games are Pepperdine, at Pacific, at USD, Portland, and Gonzaga.  St Mary's lost at Pepperdine and only play LMU and Portland once.  

In a season of odd scheduling quirks, if BYU can get the 2nd seed the Cougars would only play one game between Saturday February 23rd and Monday March 11th.  I don't really like the idea of that much time off but I'd much prefer avoiding a team like Pacific or LMU or USD or Santa Clara that have all battled BYU tough this year.  The semi-final game USF or St Mary's should be a doozy.