A timeline of Hayden's career:
1993-1997 - faced quality attacks, South Afirica (Donald, De Villiers, Pollock) and Windies (Ambrose, Walsh, Bishop):
averaged 21.
2000-2004 - faced attacks so bad that he could just walk down the pitch to fast bowlers (and i use that description loosely)and smash them where he so choosed.
Averaged 60 odd at a guess. Imagine trying that tactic against Ambrose, Akram and co LOLOLOL
2005-death? - faced a quality, four pronged pace attack, the first decent one since his first stint in the team. And low and behold he has averaged
mid-to-early 20's again.
Michael Slater and Mark Waugh both finished there careers with averages in the mid-to-early 40's If their careers had begun and ended five years later they would have averaged in the late-40's to early-50's. I have no doubt about that.
Look at blokes like Martyn and Ponting for example. As good as Ponting is, is it any coincidence that his average and Martyn's jumped from mid-40's to high 50's! (low 50's in Martyn's case) once Akram, Younis, Donald, Walsh and Ambrose retired. And it was also around the time when pitches were made to last 5 days for tv. Surely that is no coincidence, just as it is no coincidence that Hayden has only thrived during his career when facing mediocore pace attacks.
Have a look at Hayden's career graph.
http://www.howstat.com.au/cricket/Statistics/Players/PlayerBatGraph.asp?PlayerID=1976
Scroll completely to the left, then go to the middle, and then scroll compeltely to the right. Now im no f**king detective but there's clearly a pattern there. It looks like a mountain. And the reasoning behind it has been explained in the last two posts.