Wales hadn't won an away Test since they beat Japan in Tokyo in 2001 and had suffered 13 successive defeats on the road. This was also their first victory over a team ranked above them in the world rankings for more than three years since their win over France in Paris in the 2001 Six Nations championship.
Ruddock's men also became the first northern hemisphere side to beat a team from the southern hemisphere this summer.
"I'm very pleased we got the result because to win in Argentina with their reputation isn't easy. We haven't beaten many major nations in the last couple of years and this can really take us forward," said Ruddock.
"It was disappointing that we allowed them to come back at us in the second half and we will have to improve on that next week and make sure it doesn't happen again. This will do us a lot of good and give us a lot of confidence.
"But we mustn't allow sides to seize the initiative at crucial times as we did at the start of the second half. We must be pragmatic - there is a lot of hard work to do on certain aspects of our game."