I'd rather that the person who set the best average at the comp won, no matter what round it was in.
I'm not convinced that this identifies the best cuber at the tournament better than some other proposed methods in this thread.
For Fridrich solvers there is a \( \frac{15263}{15552} \) probability of a full step LL solve assuming no special techniques are used during LL beyond OLL and PLL. So the chance of getting at least two solves in a trimmed 5 cube average that are some form of LL skip is:
\( 1 - \frac{15263}{15552}^5 - 5\times \frac{15263}{15552}^4\times \frac{289}{15552} \approx 0.0033 \) or roughly 1/3% chance to get such an average.
Now, if you're good enough to make it through 3 rounds of 3x3x3 then the chance that at least one of your averages has at least 2 skips is approximately:
\( 1-(1-0.0033)^3 \approx 0.0099 \)
So each cuber who makes it to the final, and gets to do 3 averages, has an approximately 1% chance that one of their 3 averages has at least two skips. With 16 competitors making it to the final, the probability that at least one of those competitors gets at least one average with at least two skips is:
\( 1-(1-0.0099)^{16} \approx 0.147 \)
So this competition has an approximately 15% chance that the winner wins by luck, and not necessarily by skill.
A major assumption I am making here is that all of the 16 people in the final are good enough that getting at least two skips in a trimmed 5 cube average gives them a significant enough advantage to outclass the other cubers who would also make it to the final and not get such an average. I think this assumption, even if it might not be completely true now, will not be unreasonable within 5 years.
Another assumption is, of course, that other methods will contribute to this chance as well - some possibly more than this and some possibly less. This also does not include the chance for F2L pair skips, and the fact that people use advanced techniques to increase their chance of a skip in the LL. The real percentage of competitions won by luck would, I propose, be higher than this estimated chance.
Chris