Sam never does more than that, anywhere. He knows this track, too. So, no I don't think it was that.
I've never seen him ride live, but from videos one thing is clear. He's super fast over rough, steep terrain. Insanely smooth (like Vouilloz was) and no-one can touch him there.
He's not as fast where lots of pedaling is required. Stromlo seems to fit that bill. It's his 'weakness', but some would argue Stromlo isn't a good DH course, too flat, pedally and not technical enough (not my opinio, I don;t know the course).
I'd say that's why he was 11th, and that's why Minaar might well beat him overall (more versatile and all-round rider, I believe).