The current rule is that a player may place their hands on the back of their opponent to protect their position in a marking contest, provided they do not push their opponent in the back. You can’t ‘protect your position’ without applying some force, so umpires must decide whether the force was a push or a, umm, protect. You then get players out of position throwing themselves forward like they were shot out of a cannon.
It’s almost impossible to get those calls right all the time. The problem with such subjective rules is that (most) umpires don’t want to be blowing their whistle all game, so they lean towards letting them go, which means players are incentivised to push players in the back more and more, which means the umps eventually need to be instructed to pay more of them, which leads to an overreaction by the unmpires and then complaints about the interpretation change.
It’s like the tides.
The AFL tried to make it simple with the hands in the back rule, and people hated that too.
You can make peace with the fact it’s one of the most difficult sports in the world and hope that the swings and roundabouts means it averages out over time, or you can keep a mental scorecard of all the times your team has been aggrieved. Raglan Matt has the aggrieved angle covered for all of us, so I’m comfortable leaving that to him.
Chopping of the arms was the one that bugged me on Sunday. I have no idea what criteria the umps are using for that one, but it must involve mass because Darcy never gets that call.