Is there a big (i.e. noticeable) difference between the grappling ability of brown belts and black belts? If you were to see two BJJ practitioners grappling, but you did not know what belt level they were at, do you think that you'd easily be able to determine, after a few minutes, who is the black belt and who is the brown belt?
I don't think so, but then again I a newbie at this.
When answering, could you guys also comment on whether or not determining who is the black belt and who is the brown belt would be any more, or any less, difficult if they are wearing a gi or not? Assume that both guys have not trained in any other grappling art other than BJJ.
There are some black belts that got their belts just for the time they put in. They can still wreck some of the lower belts, but they dont compete much and really arent that good. Then you have some brown belts that win just about everything and seem ripe for their black belts.
Generally speaking, yes, I think you can see the difference in the levels, but it wont be that obvious so you have to have an educated eye to know what the black belt is doing that the brown belt isnt.
I've trained with purple belts who felt better than some browns I have rolled with. The level of the black belts I have rolled with has varied a ton actually. Without saying names, it seemed like the most impressive black belt I have rolled with would tap out the least impressive black belt I have rolled with pretty regularly.