Well, my team doesn't care about the freshmen. No matter how much they are better than the upperclassmen. Some upperclassmen are really annoying and butterfly.
Oh, and there's no such thing as annoying freshmen, right?
I'm sure there's freshmen that are indeed more qualified than some upperclassmen. I know there are. But in most cases an upperclassman is going to get the first shot.
As a senior and the president this year, this was my criteria:
1.) Effort. If someone's not showing effort, they don't deserve it. I do feel we could have done better in this department, as some people didn't end up putting in the time. The thought certainly crossed my mind of making a few last-minute swaps.
2.) Experience. If you've been on the team before, the experience is invaluable. Especially if you've done the event.
3.) Knowledge in subject area. The people competing in each event need to have a good understanding of what they're doing.
One thing about being a junior/senior is that you've taken a lot more classes in the subject area. I wouldn't put a freshman in Chem Lab or Physics Lab, as they haven't taken Chem or Physics. Someone who's taken AP Bio is going to be better qualified for Cell Bio or Health Science than someone new.
Since there's two people in each event, often there's a combination of upperclassmen and underclassmen in each event. This usually works out well, as it's better preparation for years to come.
This year we had 3 seniors, 2 juniors, 6 sophomores, and 4 freshmen. We did not have a lot of upperclassmen interest...the two juniors and one senior were new this year, one of the seniors had only one year of experience.
But the fact remains that in many cases the upperclassmen are better suited. You can't expect to necessarily make the team your first year...but if you show an effort, you'll be better prepared for the next year.
Now, there are some incredibly talented freshmen. I worked with some this year and they did outstanding. Our freshmen on our team did better than most of the rest of the team. One reason for that is they were in the events that they could best apply their talents, and they showed more effort than I've ever seen. There were also a lot more freshmen that I wish could have fit on the team, because never before have I seen such enthusiasm. They'll definitely do well in the years to come.