I'm a big beleiver that the tough runs in are the best.
To be Premiers have to step up. If you can't beat the best you don't deserve to be the best.
With a tough run it you get the chance to step up week after week to the best, stake your claim, and hopefully come up trumps. If you've stepped up week by week against tougher and tougher opponents when the GF comes around you'll be ready to do it again, fuelled by a genuine self-belief that you can do it. Just look at finals chokers for 27 years the Roosters in 2002 and cellar dwellers Penrith in 2003.
With a soft run in self-doubt begins to creep into a teams mind about whether they deserve to be in a GF and whether they deserve to become Premiers.
A tough run in builds the confidence needed to take out the title.
If your team going to win the premiership, its going to beat every team that stands in its way, its that simple.