Can't resist adding a story...
2-3 years ago, University of Jiu Jitsu (Saulo) I'm told to come at noon for Pan Am camp training. I'm 6-7 months out of rotator cuff surgery and not doing Pan Ams, but I'm like I better go if I have been individually and specifically asked. The usual competitors were there like Xande, Saulo, Fredson, Paulo Guiobell sp?, Leo Santos, etc. Also Lovato and his guys, and I see Kron stretching and think this should be cool...
We all line up, and Xande lines up with the class, not up front and out of locker room walks Rickson, in a gi, and announces he's running practice !-) I know the details of the techniques is what everyone wants to read (as would I) but honestly he really showed simple adjustments to basic positions but I swear to God, Xande, Saulo, other champions all were amazed like they never considered the possibility of the concepts he showed. We all just were like "that's so simple, why isn't this ever taught?!?"
And the training....

Diego Sanchez gets matched up with Kron in a 10 minute match with score counting. Diego hits 2-3 takedowns and 5 minutes left passes the guard and holds Kron pinned for 4 minutes with Rickson imploring him to escape. He escapes and guilotines Diego with 10 seconds to go, lol

and Diego disappointed in his self, no matter at 9:30 he was up like 9-0 in this scrimmage match, lol. Demonstrates how damn calm and patient Kron is, it was amazing.
I believe this was same day Cleber and Megaton had a WAR and tempers got way over heated. Same thing 10 minutes, starting standing with score kept. Imagine the pressure with all those champions watching, cheering, coaching....
Everyone wants to know I'm sure did Rickson roll?.... He did, and only with the best black belts, and since they all are so respectful of him and refer to him as Professor, I don't think it's taboo to generally mention how those rolls went. Let's just say Rickson started in mount and always escaped, and reversed the position after 5-6 minutes and no one escaped. Yes he did this with Xande (who was current world absolute champion) and Saulo (who was one year removed from 2nd place losing to Barral on points after beating 4 guys including Tarsis), and Rickson, with all due respect, had really looked like he had aged a bit and did or does not have the physique we all remember 10 years ago. I'd estimate he was 155-160 lbs at most. His technical flow was just overwhelming guys were commenting after.
The adjustments Rickson makes so subtle are what people refer to as his "invisible jiu jitsu." I've trained many times with most dynamic, progressive BJJ guys like Marcelo Garcia, Andre Galvao and Rickson didn't show any mind blowing positions like those guys...
Small example, problem was guys almost in full mount but their foot caught, like 1/4 guard, and Rickson asked all black belts what to do.... He simply showed how to grab the collar and make his head turn opposite side, and ur foot easily freed.
I know this example sounds to simple it's stupid, but the day Rickson showed techniques there were like 20 Mundial medalist competitors present and none of them could answer his questions, it was almost supernatural
And to re-iterate, Rickson did not just teach on the side he rolled with the best of the best and he never was in a single bad position, and dominated everyone he trained with. I'm a believer, I saw it....