The old "how did he catch me" or "that move was impossible" complaint. We've all been there and thought that a time or two I'm sure. Usually 99.9% of the time, the .1 representing internet lag, these situations are easily explained by reviewing the film from incident. I know for me personally, the odd time I've thought that something seemed impossible or strange, it's nearly always been a case of lack of situational awareness. I.E. - I just didn't see the aircraft in question start his dive, or whatever, and when I eventually did pick him up visually, it seemed strange for X or Y type of plane to be moving so quickly.
Again, I don't think it can be repeated enough, if you have a moment of WTF-ness, look at the film, and put yourself in your enemies point of view as well, PRIOR to making a wah-post about it on the BBS.