Thanks to BJ's observation below (see comments), the analysis of the original post is pretty much wrong. Even though the muscle up should have been worth quite a bit (considering the percentile chart below), HQ is awarding the highest ranking points to tied individuals instead of the lowest. So if you score a 90 (ie where the big vertical line is in both men and women on the plot below), you are awarded the percentile score at the top of the vertical line. I had incorrectly assumed that the rank score for 90 would be at the bottom of the vertical line.
The corollary of this: the last OHS is one of the most important reps you can complete!
Thanks again, BJ, for pointing this out. I have left the evidence of the previous post so people can make fun of me.
Also, by popular request I have started to look into the age vs performance question, and yikes... the plots are pretty grim, especially on the men's side. Stay tuned...
This post discusses the fourth 2011 crossfit open workout, described here.