First the average GMAT of 690, as PlastMan mentioned, is not significantly lower than LBS, which has just recently increased from 690/5 to 700. The highest ranked programs in Europe (LBS & INSEAD) both have average GMATs of 700. This is most likely a function of the number of non-native English speakers attending these schools.
Secondly, both LBS and INSEAD are rumored to have acceptance rates that fluctuate significantly. Some say INSEAD & LBS acceptance rates are over 25% in certain years, and others state LBS as low as 13%. My guess is that it is somewhere in between. The fact that they don't publish their acceptance rate suggests that it is much higher than comparative US schools that all tend to be under/around 20%.
Lastly, I don't think you can discount the salary figures so readily, PlastMan. Judge is a 1-year program and attracts a different type of student than LBS. The average age tends to be slightly higher at Judge and people are likely further along in their career. When these people graduate and take jobs in industry (versus consulting/banking) they will command a higher wage in the market.
i think you will continue to see Judge climb in the rankings. It is a relatively new program, but you cannot discount the brand of Cambridge, and their career statistics are on par with LBS and US programs ranked 8-12. I wouldn't be surprised to see it surpass the Spanish schools, that have no name recognition outside of Europe, in rankings other than the FT in the next few years.