2 sides to every story is what i'm thinking
new guys in advanced class?
we have an advanced grappling class too and it's all about warm-up, drills, +++ rolling and +/- techniques.
we had some new guys exclusively come to advanced class and then wonder why they didn't progress - we told them to go to jiu-jitsu class to learn the basics and more technique.
getting choked and elbows tweaked?
what? did you expect, as the new guy, to be the one choking people out and slapping armbars in an advanced class?
weird thing is, you're actually learning when someone hands you your ass - some people realize it right away, others need further reinforcement.
check the ego at the door.