Over the same period the average number of runs scored against Australia per wicket taken is 30.12. Shane Watson's Test cricket bowling average is 31.96.
Which suggests to me that Australian Test cricket, in evaluating the value of its players, could introduce a variant of the baseball statistic Wins Above Average Player. They could call it Wins Above Shane Watson.*
*In defence of Watson:
P.S. Australia's players have, on average, been better than Test cricket players overall.
P.P.S. An average player is still better than a 'replacement level' player.
P.P.P.S. And anyway, it is quite OK to be an average Test cricketer.