Regarded as New Zealand's greatest coach,Muir wasn't completely surprised when Noeline Taurua's team broke a 16-year drought by toppling the No.1 ranked Diamonds,who were heavily favoured to bag a 12th world crown.
She said resilience built on years of Kiwi"suffering"was the difference.
While New Zealand boasted four Test centurions - Laura Langman,Maria Folau,Casey Kopua and Katrina Rore - Australia went into the tournament with only captain Caitlin Bassett having exceeded 50 caps.
Bassett's team,so used to dominating,looked lost when New Zealand opened up a gap.
"Australia,really,has never had to fight as hard as us,"Muir told AAP.
"They don't handle it as well when they have to come from behind because they haven't done a lot of it.
"That's what the crux of that final was and those older,experienced New Zealand players had control of that game."