My two cents worth. This rivalry is the 7th most contested rivalry between two teams in the same state.
Lehigh vs Lafayette - 161
Richmond vs William & Mary - 136
Oregon vs Oregon State - 129
Cincinnati vs Miami (OH) - 128
California vs Stanford- 128
Indiana vs Purdue - 126
Montana vs Montana State -124
in my short lifetime of 80 years I have seen the rivalry between both teams grow stronger.
The rivalry has always been a battle, but it was civil after the game. During the later years of the streak of the last part of the 20th century it became a little more common to see the animosity between fan bases.
Since the turn of this century the record is Griz 13 and the cats 12. Many times the Brawl has been a deciding game for the conference champion during this period.
Good, bad or otherwise the animosity between the fan bases has become more intense.
Both sides have displayed awful behavior towards the other many times.
While those displays are subjective, I believe that the cat fans have been on the losing side of the spectrum. I believe it is a byproduct of the streak.
Griz fans, don’t beat the drums to loudly as there are many that have taken it way too far as well.
I will end with this statement, regardless of how ugly each side of this rivalry has been, I think it pales in comparison to Ohio State vs Michigan.
I had the opportunity to attend that game many years ago, that was true hate.