It seems like it was a bad idea to have people climbing in the gully above where the ice climbing was occurring. Why were there people above? Since this was apparently a competition, why was this allowed? The climbers who triggered the avalanche must feel awful.
I think they were all headed for the same group of routes above Silken Falls. The upper group was being really cautious. The comp format is pretty much go for what you want, and any parties that climb the same route split the points. There is not much guidance or oversight for who goes where, especially in the invitational. It's not unusual for parties to climb the Dribbles and head over to these routes (called the Climbs Above the Dribbles, but actually in the gully above Silken Falls) while other parties, unknown to either group, are climbing below.