Wales' 26-12 defeat was their heaviest home loss for three years and biggest reversal anywhere since subsiding to France in Paris 22 Test matches ago.
It also left their hopes of securing a top-four seeding at the 2015 World Cup in tatters.
With next month's tiered draw being based on global rankings, Wales might even find themselves outside the top eight by early December given that their next three opponents are Samoa, New Zealand and Australia.
Life is not about to get any easier for last year's World Cup semi-finalists in terms of their autumn fixture list, while key players Jamie Roberts and Alun-Wyn Jones have now joined a pre-Pumas injury list that included Adam Jones, Dan Lydiate, Jonathan Davies and Ryan Jones.
While centre Davies and back-row forward Ryan Jones could be back in the mix for next Friday's Millennium Stadium appointment with Samoa, it looks likely that Roberts (concussion) and Jones (shoulder) will struggle to play Test rugby again this year.
The combined effect of those first half departures contributed considerably towards Wales seeing a 9-6 interval advantage disintegrate as Argentina recorded only a second victory over Wales in Cardiff - 11 years to the day after their first.
"We just didn't play in the right areas," said 91 times-capped prop Jenkins, after tries during six second half minutes by Argentina wings Juan Imhoff and Gonzalo Camacho stunned Wales.
"We didn't really look like scoring at some points of the game. It's back to the drawing board.
"Argentina came with a game-plan to kick a lot and be very physical, but we played into their hands, really. We tried to play too much rugby inside our own territory, and I don't know whether it tired us out when it came to the last 25 or 30 minutes.
"They seemed to up the tempo and we couldn't live with it. We let in two soft tries and I suppose our spirit went down a little."
Argentina arrived in the Welsh capital battle-hardened from their debut Rugby Championship campaign, and they gloriously showcased the benefits of tackling southern hemisphere heavyweights New Zealand, Australia and South Africa on a regular basis.
Jenkins added: "I have played against Argentina before, but they've definitely gone up a level from where they have been.
"Playing six games against Australia, South Africa and New Zealand, they are going to be adjusted to that level of intensity. Every time you play a Tri-Nations team it is a step up.
"But we didn't perform. We made mistakes, we lost the ball quite a bit and we weren't on our game. We hate losing at home, and it was a really depressing changing room afterwards.
"We tried to play too much. I know that's a negative thing to say, but you look at the top teams and they play in the right territory and put pressure on their opponents.
"There is no time for us to dwell on it. We are straight back into it to prepare for Samoa, and we've got to look at ourselves after this game and see what we can do better."
Wales' interim head coach Rob Howley, in charge while Warren Gatland begins preparations to head up next summer's British and Lions tour of Australia, admitted his team were "one-paced".
But he must also urgently address the anonymous performances of several key players - skipper Sam Warburton included - prior to a Samoa clash that has danger written all over it.
Wales have won just three of their last six meetings with the South Sea Islanders, and two of those were only by seven points or less.
Howley's dilemma is whether he gives his Argentina flops a chance to show they cannot be that bad again, or shakes things up.
Whatever he decides on, the Ospreys trio of fly-half Dan Biggar, hooker Richard Hibbard and flanker Justin Tipuric must start, while there is a strong case for Bradley Davies and Luke Charteris to be the starting locks.
A Welsh pack battered beyond recognition by a mighty Pumas eight inspired through the magnificence of captain Juan Martin Fernandez Lobbe, needs urgent attention.
"I am disappointed, frustrated and annoyed because we know we are a better side than that," Howley said.
"When you play Argentina, tempo, pace and intensity are important, but there is no doubt their experience and exposure to the Rugby Championship has taken that Argentina side to another level.
"They played the All Blacks, South Africa and Australia over a six-week period. They have certainly learned from that and we were exposed to it. We very much came second."
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