I think my views can be summed up pretty succinctly:
1. There is no such thing as 'Oxbridge standard', as attractive as it sounds.
2. A few amazing people will always slip through the net, but in most cases there is probably one part of their application that seemed weak. (Perhaps they were much better candidates than the application process revealed. I'm sure this happens a lot, and I remember back when I applied that I was dead worried I would be one of these people. [EDIT: Not trying to sound arrogant or anything!!])
3. Not everyone who gets into Oxbridge is all that bright, though the majority are.
4. The admissions tutors do the best they can, and do a reasonably good job considering...