The South Americans were added to the Rugby Championship five years ago and founded the Jaguares franchise to play in Super Rugby last year.
After New Zealand capped their fifth southern hemisphere title victory in six years with a 36-10 win over Argentina in Buenos Aires, Hansen said that the extra travel was taking its toll.
All Blacks coach Steve Hansen. Photo: photosport
"The long distances are always tough but since Argentina were brought into the competition the travel has become a big thing.
"We pay a price, not so much in this competition, but when we go on the end of year tour (to Europe)," he said after arriving from a two-day, three-flight and seven time zone trip to Cape Town, where his side take on South Africa next Saturday.
"Australia, South Africa and ourselves are doing the same so it's no coincidence that since the travel has been greater, that the results have started to change a bit up north."
To try and counter the fatigue, Hansen left six key players out of the trip to Argentina with lock Sam Whitelock, loose forwards Liam Squire and Sam Cane, and backs Lima Sopoaga and Ryan Crotty arriving in South Africa last Friday.
Sam Whitelock was among a group of six players who went straight to South Africa. Photo: Photosport
Brodie Retallick was also supposed to be part of the group but has stayed at home in New Zealand after his wife miscarried.
Vaea Fifita, Ngani Laumape, Waisake Naholo, Luke Romano and Ardie Savea - who all featured in the win on Saturday - have returned straight home.
"We struggled at times last year, this is the hardest time of the year for us, so we are just trying to think outside the box and think of ways to keep the players fresh," Hansen said.
"We're learning as we go along and that's why we are trying something a little different this time by splitting the group. We could have taken 32 here and 32 to Argentina but we've decided to only bring 28 and some guys to one venue and not both.
"Is that going to work? I don't know. We'll have to wait and see once we're finished in Cardiff to see whether it has worked or not."
After their last game in the Rugby Championship at Newlands on Sunday morning the All Blacks play Australia in the third Bledisloe Cup test in Brisbane before embarking on their end of year tour with games against the Barbarians in London, France in Paris, the French Barbarians in Lyon, Scotland at Murrayfield and Wales in Cardiff.
-Reuters
