Priit's defense techniques are a game changer. I'm a white belt and I noticed a black belt instructor staring at me roll when I was just laying there in a lazy posture protecting the underhooks by bringing my arms in. The other guy was confused lol.
Some of them show up in random places. Like I think I saw something very similar to the babybridge used in a bottom side conrol escape by Pedro Sauer. You'll see that arch that the body forms get used a lot in areas like when you use a knee shield in bottom half guard and extend your upper body away.
Priit doesn't really compete himself. You have to look at Priit's students/colleagues, like Martin Aedma. Check Priit's own DefensiveBJJ channel for some Priit's rolling footage.
I had a chance to roll with Priit last year at the Globetrotters camp in Maine. It was an eye-opening experience! I realized that over the years of watching his stuff, I'd never actually seen him do or teach a submission... was interesting to see what he used to submit me (wrist lock!).
