Murphy has to play 4 games against #1 OSU, 4 games against #2 Wisconsin, 4 games against #9 UMD and 4 games against #10 Saint Cloud. Not including the WCHA playoffs. Murphy is putting up her numbers against the best weekend and week out. The others rarely have to be tested. That being said...the Patty is not just about stats but about the overall athlete. The on ice performance, locker room and off ice achievements.
The WCHA is clearly the best league, but most of the commenters on this board are fans of WCHA teams, which results in something of a bias past what's reasonable. Since there is apparently a Patty Kaz voter reading it, it's worth clarifying - Cornell has played the #11 ranked strength of schedule (according to myhockeyrankings), Minnesota is #7. That is a gap - but hardly a gaping chasm. (#1 through 8 in SoS are WCHA schools - so the stats agree about the conference, although Minnesota plays the second easiest of the WCHA schedules).