Expectations are always high in New Zealand when it comes to rugby and a 40% win rate over his first five tests in charge have led inexorably to calls for Foster to be sacked.
"The first and most obvious thing to say about Argentina's brilliant win over the All Blacks, from a New Zealand point of view, is that Ian Foster must go," columnist Chris Rattue wrote in the New Zealand Herald.
Gregor Paul in the same newspaper said the team had been reduced to a "shambolic, unimaginative, uninspiring body of players that couldn't catch, couldn't pass, couldn't win their lineout ..."
The extent of the shock of Saturday's defeat against an Argentina side which had not played for 13 months can be gauged by Stuff.co.nz's preview of the contest, which rated the Pumas chances of a win as close to zero.
"Between Foster sending out the heavy artillery and this being the Pumas' first test since the World Cup last year, things are just stacked too heavily against them," it read.
Foster's heavy artillery misfired at Western Sydney Stadium, however, and the Pumas conjured up a performance for the ages to win 25-15.
That came on the back of last week's 24-22 loss to Australia in Brisbane, where a young Wallabies side coached by New Zealander Dave Rennie also found the All Blacks wanting under pressure.
In the plus column for Foster, his team had already secured the Bledisloe Cup for an 18th straight season after a 16-16 draw and two thumping wins over the Wallabies.
His immediate predecessors Steve Hansen and Graham Henry had win records of 86.92% and 85.4%, however.
"Five tests, two wins, is grim reading in anyone's book," another Herald writer, Liam Napier, wrote. "For a team with lofty expectations such as the All Blacks, it's completely unacceptable."
The All Blacks have only the rematch with Argentina on Nov. 28 to restore some pride and anything short of a handsome victory could bring a summary end to Foster's reign. (Reporting by Nick Mulvenney in Sydney; editing by Jonathan Oatis)