BC by 45+
Because the most notable common opponent was Buena Vista,
BC 52- BV 0 over at half
GC 52- BV 36 full game
The other 2 common opponents(Sterling City, Klondike) don't give a true comparison, because they could both be 45'd by an average team. Unless someone has the defensive numbers allowed to these teams by GC & BC (1st downs allowed, yards allowed etc.).