I get the theory but it makes less sense when you look at Brisbane and Hawthorn hat-tricks and particularly when you consider the same comments were made in 2004 after playing in GFs the previous 2 years under the same coach.
The reality is there would be some truth to all then theories from physical work load, mental drain, celebrating, MM's frame of mind, GF day coaching, the Shaw/Maxwell suspensions and injuries (probably forgotten some usual suspects) but the fact it we had more wins in a season than any year in our history, it was our first premiership defence since the 1930's (didn't make a following year GF since the 4 in a row) and we were right in the GF for 3 quarters of it.
One comment that Pendlebury made was about the trip to Arizona, especially after the unscheduled GF replay. Then a serious Preseason, winning the GF and playing more football than any other team.
Perhaps it was too much. The benefits had all worn off by the time it mattered later in the year.
Interestingly one of the first things Buckley changed was cancelling the Arizona trip.