Meh - all relative. I visited a BJJ club as a 1K brown belt. In my first session I tapped a blue - doesnt mean I'm better than blue belt level, I was just stronger & had the bloke's number on the day.
Consider that there are different expectations of a black belt judoka depending on the country. In Japan, shodans are not necessarily experts as they take a different view of black belts - whereas in Australia shodans are somewhat tougher - you cannot get a shodan in 1-2 years in Australia unless you are really exceptional technically & in competitions. There's a different set of standards for every country.
I think labelling judoka black belts = BJJ blue belts on the ground , or BJJ black belts = judoka blue belts in standing is really too subjective - given the varying degrees of skill and standards from one individual in one country to another individual in another country - to make any accurate general comparison.
