Here are the stat lines for those two players. Might help shed some light on how the model tries to compare two players:
Petterson against Towson:
Unassisted Goal - 3
Assisted Goal - 5
Ground Ball - 3
Saved Shot - 2
Unforced Turnover - 1
Forced Turnover - 1
Penalty (1 min) - 3
Total EGA: 4.99
Tuttle against Hartford:
Unassisted Goal - 4
Missed Shot - 5
Ground Ball - 5
Assisted Goal - 1
Assist - 1
Blocked Shot - 1
Saved Shot - 1
Forced Turnover - 1
Total EGA - 7.06
I think the bigger gripe I would having in trying to compare these two would be based on the strength of the opponent. Hartford is one of the worst teams in D1. But part of the point of this list is to highlight players who had a great game who may not get a lot of national spotlight. Adding an opponent adjustment would make that impossible.