Any cheerleader really does know the risks when they get to this level in terms of injuries etc. Cheerleading is the most dangerous female sport - presumably that is serious injuries/fatalities per participants???
Monica's point about the guy being injured in another club was because they are on a a scholarship to the college worth an awful lot of money and tbh they shouldn't really be in other clubs exactly for that reason, and certainly not in the months running up the major competition...
Every time someone is out due to injury it impacts on the rest of the team. It isn't easy just to slot someone in you have to relearn how to do that stunt move with the revised stunt group.
When the bases just weren't there to catch sherbs, that's the consequence of 2/3 people not focusing properly for a few seconds 
none of them were remotely in the right place.
Although it's a documentary it's still heavily edited. I'm sure if you compare it to a football manager it's just as cut throat - it is all about winning! How they test their youth leaves a lot to be desired too. I'm sure there will have been prize money involved.
I'm on the fence, how far I want my DC to get - they compete at level 4 now and they were at the top which is level 6 (or possibly they have introduced a 7 now). But serious injuries can be from a simple stunt, recurrent concussion, them being stupid and stunting not on a proper sprung mat.
Another DC plays rugby, several concussions, fractured spine, broken nose and other injuries so far...