Because 2015 was a First 4 appearance as an 11 seed, it's to be expected that BYU would win 0.81 games that year (instead of 0.61). Basically the idea is that there's a 50% chance they lose (0 wins) or a 50% chance they win (+1 win) and then move forward as a 'normal' 11 seed (0.61 games).

So 0.50 * 0 wins + 0.50 *1.61 wins = 0.81 wins expected

Doesn't change the overall sentiment though - in particular 2010-2014 were years that we overperformed our seed. This last season profiles as our worst underperform (in the last 10 tourney appearances, which is as far back as I looked)