Melbourne never made finals with Paul RoosIn any kind of success it's human nature to overestimate skill and downplay luck when looking back.
He's clearly a very good coach, but there's obviously an element of luck around the staff, players, resources, injuries that factor into it as well.
He should be able to get north competitive again the same way Roos did with Melbourne but I wouldn't be expecting miracles. They're probably at least 3 years away from competing for a top 8 place.
Every single club in the AFL currently uses the defensive zone Clarko implemented. Hawthorn won a flag in 2008 solely due to the advantage they had as the first implementer of that.
That is not luck.