More than half of Australia's Tests were played at home.
5.5/10 at home
1.5/10 in India & West Indies
1/10 ..in England
1/10 ..in South Africa & New Zealand
1/10 ..in Pakistan & Sri Lanka
something like that..
So if a player is crap in SA and NZ, they are only 1/10 (one tenth) unsuccessful. Most important thing is to be absolutely great at Home because thats where >50% of your matches are.
So I think people are giving way too much importance to performances in individual away countries, forgetting about the really low volume of matches a player plays in such countries. So whether you avg 35 or avg 50 in an away nation could be all done to luck or prevailing factors -
Factors such as - when you toured each time, your overall form heading into the tours, type of pitches you played on, weather conditions, situations you faced, morale, match & series position, bowlers you faced, catches caught/dropped, form of opposition bowlers, magic balls, rub of the green, your form vs certain bowlers, how well/poorly they bowled, grounds you played on.... list goes on..