Sir Graham Henry says the All Blacks' will to win in every test match gives a false read for the World Cup.
The All Blacks have been portrayed as Webb Ellis chokers because their record does not live up to a consistent ranking as the best team in the world.
Henry, writing in the Guardian, said: "I've come to appreciate about the tournament, having had the privilege of coaching a team in three of them, that world rankings and being the favourite count for nothing.
"It is the major focus of all rugby-playing nations...only New Zealand have an expectation of winning every test: their percentage record leading up to the past three tournaments was between 81 and 88 per cent.
"A consequence of this mentality, which I am not criticising, is that New Zealand do not improve as much as other nations. You can expect other countries to play better in a World Cup than they normally do, as I found when coaching the All Blacks in 2007.