The reason Petrie dominated him in the 3rd quarter was because he got the 1st mark so easily- absolutely no body contact from Chaplin. He actually boosted Petrie's confidence with his softness. What a soft defender, he was supposed to free up Rance but at what cost, he is not tall enough, not strong enough but overall just not good enough to hold down a key post.
There is a quirk in the 'in the back' rule that Chaplin needs to take advantage of if he is playing an opponent 5 inches taller. While it is expressively forbidden to even place the palm of your hand on your opponents back, it is seemingly ok to arrive at a contest a fraction of a section late and drive your knee into your opponents back. Rance has become a champion of doing this and making it look accidental and whatsmore he will then fall on top of their 'breadbasket' making it difficult for them to breathe. All this supposedly when you can't 'do much' these days, and in a way Chaplin is a product of the soft serve variety of AFL, however there are still ways you can make them 'earn' it and ways that you can make them 'think twice' next time they are reaching up for a mark, but I just can't see Chaplin as the type of person that has that type of aggression in him. He is weak.