I think experience is key - but to be more specific, winning experience is key.
Experience is especially useful when making decisions under fatigue and/or pressure, and at helping to lead your team through the tough times.
For example, would a side benefit more from having Andrew Ettingshausen (or Nathan Hindmarsh) in a Grand Final qualifier, when they are up against it, or Anthony Minichiello?
Both Hindmarsh, and Ettingshausen, played more games than Minichiello - but Minichiello played in more Finals wins (and won more Premierships).
The experience that Minichiello brings to the table is more valuable than those of Hindmarsh, and Ettingshausen - it's not that Hindmarsh, and Ettingshausen, don't bring experience to the table; rather, their [relative] lack of comparative success indicates that they may not be a cool enough head under pressure to make the right decisions.
Experienced winners are very influential.
If we keep making the Finals, and start winning more Finals, we will massively benefit from it.