With two matches left of the Rugby Championship, they've already broken new ground this season, winning two matches for the first time.
In six previous editions they had finished bottom of the pile five times, and in two of those they lost every match, including last year.
Argentina suffered a dire June campaign where they lost twice at home to Wales before being drubbed by visiting Scotland, conceding 10 tries and almost 100 points in total, after which Daniel Hourcade was replaced by Ledesma.
"It's a positive return, very positive. Something's happening in this team, you can sense it," said Ledesma 10 days ago, following a first victory in Australia in 35 years, and first such in the tournament.
Ledesma honed his tough playing style in France, where he began his coaching career before developing it in Australia.
"He was fed on French and then Australian rugby. With him, Argentine rugby has a great future," said Andrés Courreges, a hooker for the Pumas in the 1980s.
Those coaching positions on foreign shores were as part of the backroom staff, but Ledesma cut his teeth as the head man in a hugely successful six-month stint in charge of the Jaguares, Argentina's sole Super Rugby participant.
"They don't play for the sake of playing. They don't play for fun. They play to go forwards," he said. "That's the way it is. We can score a try from 80 meters out, just as well as we can spend 10 minutes kicking it if that's what the game demands."
Ledesma has helped players tap into the spirit of the last line of the Argentine national anthem, sung before the start of every international match: "we vow to die with glory."
"Whereas once the players were happy just to be wearing the jersey, now they put it on and honour it," added Reggiardo.
When it comes to the World Cup in Japan, a resurgent Argentina will be a worry for their pool rivals, England, and in particular, France.
In the 2007 World Cup in France, Argentina beat the hosts twice on route to their best ever finish of third place.
Only two of the three can qualify from the pool in Japan, and the other two won't be relishing playing a Pumas side on fire.