I'm not one to really comment on these boards; more often than not I'll post a question for my own purposes to be answered by men and women much smarter than myself. I will say, however, that the characterization made by GSdad seems a bit, well, one-sided.

I was at the game, and saw the physical play right from the beginning. Yes, Northwestern engaged in what might be referred to mildly as "chippy" play. I also commented to those around me (at least those who were listening, including my six-foot rabbit friend Harvey) that such play was detrimental to the system Northwestern had executed all year.
Irmo (or IRMO or irmo or whatever) controlled the pace and tone of the first half because of their willingness to bang bodies and make themselves a nuisance to the Trojans. One might consider their play "dirty" as you have characterized Northwestern. From where I sat, there was clearly a lot more jawing on the part of the players in black (but then again, I was sitting kind of near the press box, so couldn't see everything).
My main point is, both teams played hard, physical and, at times, beyond the rules. Actions by players on both teams (Martinez, Benson, Acree, Varney) and by fans on both sides were not the most positive. While I hate to just say that it's emotion and "just part of the game," I also won't go so far as to call high school kids "dirty" or "classless" when I, as a grown up, have seen far worse from the men and women who should be role models for the young fans.

There. I'm finished. Harvey and I are going to bed.