Not really a theory just a term for when a team is in the sweet spot for contending.The premiership window is a theory, and not even a scientific one.
Our list needs an upgrade or 2 but we have the cattle to win it. The club ought to be reviewing our performances this year and to be prepared to make the tough calls.
We all know the AFL is cyclic. What goes up must come down. Outliers happen like when teams try trade in to extend the window or avoid truly bottoming out (Norf for a decade and Hawks recently).