You might want to follow along on a sample scenario –
https://goo.gl/KBMK04 (CHN You Are The Committee)
With a single loss the weekend, the highest Boston College can climb in the PWR is #15 (see College Hockey Tournament Possibilities). That happens in about 10% of the scenarios in which BC loses its semifinal. However, even with that ranking, BC would additionally need the conference tournament winners to be such that #15 gets an at-large spot.
The key to BC’s PWR ranking in this scenario is idle Providence falling from #12 to #16, allowing BC to rise to #15. In this example, Air Force, Penn State, and Ohio State all do well enough to take the comparison w/Providence (on the basis of RPI), pushing Providence from 47 comparisons won to 44. BC, staying at 45 comparisons won, climbs to #15 overall.
The other necessary ingredient for BC to advance in this scenario is for the #15 team to advance, which requires only one conference tournament be won by a team outside the top 15. Because the WCHA winner must come from outside the top 15, every other conference must be won by a team that ends in the top 15. Those possibilities include:
Big Ten – Minnesota, Penn State, or Ohio State
ECAC – Harvard, Union, or Cornell
Hockey East – any
NCHC – any
Atlantic Hockey – Air Force