By Ross Dellenger A fiery media day displayed rising tensions toward rival leagues and departing schools. But it also showed the conference isn’t backing down. View the original article to see embedded media. LOS ANGELES — On Friday afternoon, from behind the buffet line at Pac-12 media day, an attendant watched as people in team-issued gear paraded through for two hours. A confused look crept across his face. Finally, the attendant leaned over the dish of chicken fajitas and, in a low whisper meant for only one person, asked a question. “What is the Pac-12?” It’s complicated. What actually is…