BYU's position is tricky but far from desperate.
The Cougars failed last weekend to earn a nearly certain at-large berth to the NCAA final four. BYU would have clinched the the MPSF regular season title with a pair of victories over UCLA, but though the Cougars did win the replay of the first match (the second replay, that is (for your own good, do not click on this link)), the controversy-tainted defeat galvanized the Bruins who then force-fed BYU one of its worst losses of the season.
BYU could still end up on top of the MPSF standings depending on how a number of other matches go this weekend. However, rather than wait and hope, the Cougars will try to make their own case for NCAA inclusion when they host #7 Penn State for a pair of matches tonight and tomorrow.
PSU is a non-conference opponent and can therefore neither help nor hurt BYU's MPSF standings, but victories over the highly ranked Nittany Lions would greatly enhance BYU's NCAA at-large profile - not to mention help the Cougars get into form for the conference and (hopefully) NCAA tournaments.
Your rooting guide: If USC loses even one of its matches this weekend, BYU will be the #1 seed and will have homecourt advantage through the MPSF tournament. If USC wins both, however, a UCLA victory over Stanford gives BYU the #2 seed and homecourt advantage through the semifinals.
The BYU/PSU matches will be at 7:00 MT on BYUtv.