Ed,
I agree that my method does not reflect improvement from Regional to Regional. However, 69.5% of the teams only attend one regional, 28.9% of the teams attend two regionals, and 1.6% attend three or more regionals. The quick and dirty list does show dominate regionals that are ~3 times stronger than others. The use of the world rank data would probably produce a fairly accurate strength estimate. While the correlation is unproven, I'll bet the the winners of stronger regionals are dominating in the FIRST Championships.
