I'm not saying those guys are specifically better. Collins is an elite intercept mark (historic numbers in the VFL last year) but he's not the stopper Moore is and in overall game is behind. Weitering struggles defending the lead, he's having a good season but he's not on Moore's level yet as a younger player.
Walker I'm liking a lot and he's probably better as an intercepter than Moore but not as athletic, as skilled or as good of a stopper so just behind.
Overall I see it as there are an incredible number of really exceptional key defenders in the competition.
The main point of contention as been that many feel Moore is an All-Australian this year and I'm not prepared to agree. This year I'd be picking McGovern and Hooker with Stewart as a third tall. Though there are another 10 or so exceptional key defenders with the players at that position really evolving over recent years with the quality of key defenders the best it's ever been with all these intercept marking and contested marking key defenders and few plain stoppers who don't offer anything else.
Cake Hooker has played four of the seven games this year dude, what are you talking about? Blicavs deserves to be the second best defender and Pearce the best. Putting Walker in there is just being a contrarian. Moore is very good overhead, but his real strength is being better on the ground than his opponent. There wouldn't be a player 200cm who is as agile and better below his knees.
McGovern has been decidedly average (for him) this year. He'd still be my third choice, so overall I agree that Moore is not in AA contention. But if his body holds together for another 15 games and he trends the way he is, that could very well change.