Yes, I saw that frustration in Cumberland in the Footscray game. It is a bit of a balancing act I think. He was clearly p!ssed off with himself, and that is a good thing as he is expecting better of himself. It gets called petulance because he shows it. What he needs to learn is to internalise that frustration and shelve it away for later. Yes, expect more of yourself, but also give yourself a break sometimes, Australian Rules at the highest level is a hard game. Plus, don't pause to dwell on mistakes at the time, think about it later with some time for reflection and in the moment just go to the next contest.
These things are more a reflection of lack of experience and stepping up to the highest level. I am confident he will learn how better to deal with his mistakes, accept every player makes mistakes and learn from the mistakes.
DS