this where they could have started with their changes, or at least have the understanding that their voice is too far behind the reactions and let it go because they know they man on the mark only went over AFTER the ball possessor had moved. They've been way too pedantic about this in the past. The ump could have gotten caught swallowing or coughing when the guys plays on etc.Same in regards to the allowed movement - seems that when it was first discussed last year it was minimal lateral movement of that 1m - 2m, then it was up to 1m and now they've decided to scrap any movement, and I guess considering how umpires can't tell what 15m is that some may have trouble telling how far 1m is
Apparently the umpires are going to be quicker to call play on should the player with the ball step off their line - would bloody hope so because if the man on the mark isn't allowed any lateral movement without it being a 50m penalty then the player with the ball shouldn't be allowed any lateral movement either
I also think they could organize themselves better in these situations. One places the mark and is responsible for encroachment. Another has made sure he has line of sight with both players and he is one who calls play on and going early. Something along these lines.
But the simplest solution, like most in AFL is to just use good judgement about whether the defensive player went before the actual going off the line, NOT the ump's sound. Hell, every other rule is adjudicated subjectively anyway; why not this one?