The 49-Test fullback scored a brace as the Crusaders ran in five tries to two for a bonus point win that maintains pressure in a tight New Zealand conference.
It was the sixth win on the trot for the seven-time champions and Dagg provided the impetus as the Crusaders raced to a 22-3 half-time lead, scoring one try and setting up another.
He followed up with a spectacular solo effort after the break to end hopes of a Jaguares revival, brushing off two defenders as he raced to the line.
The 27-year-old, discarded for last year’s World Cup then sidelined with a shoulder injury, is a certain contender for an international recall if he can maintain such blistering form.
It was the sixth defeat in a row even though they were nearly at full strength after squad rotations, leaving them with a single win so far in their debut season.
“We had a bad game, especially in the first half, but it’s part of our learning curve,” assistant coach Felipe Contepomi said.
“The Crusaders are one of the best teams in the competition and we made a lot of unforced errors. It’s disappointing.”
The Crusaders almost had a try in the first two minutes after stealing the ball in a lineout, with the Jaguares stopping Nemani Nadolo just short of the line.
Andy Ellis made no mistake three minutes later, touching down after Dagg slipped him a defence-splitting pass.
The Crusaders then ran away with the match, notching two tries when Jaguares fullback Joaquin Tuculet was sinbinned for slowing down play.
Dagg took advantage of the extra space for his first five-pointer, then Richie Mo’unga stripped the ball from Jeronimo de la Fuente for another to make it 19-3.
A Mo’unga penalty then made it 22-3 at half-time.
Facundo Isa clawed one back for the Argentines after the restart, darting from the back of a maul then powering past Ellis.
The Crusaders restored their dominance with tries to Kieran Read and Dagg, although Santiago Gonzalez Iglesias crossed for a late consolation try to the visitors.