Huddersfield had gone eight games on the road without scoring and not won away since beating Crystal Palace on the opening weekend of the season.
But the Tigers took full advantage of some rash Watford defending and a first-half red card for Troy Deeney to score an emphatic victory, which moves them up to 11th in the table.
“I think a lot of people didn’t expect we are where we are at the minute,” Wagner said.
“We have to make ourselves independent from pundits’ predictions. It is irrelevant for us.
“We are so humble and so calm. We know what size of club we are, our budget. It is not comparable with any other budget here in the Premier League.
“But we are ambitious. We say, ‘trust in yourself, be focused’. So far the players have done very good but it’s only the mid-point of the season, nothing more. We can improve.”
Elias Kachunga and Aaron Mooy put Huddersfield two goals up in 23 minutes at Vicarage Road before Deeney threw himself two-footed into the back of Collin Quaner.
Referee Michael Oliver showed no hesitation in showing him a red card.
Laurent Depoitre added a third for the visitors shortly after half-time only for Huddersfield’s Jonathan Hogg to be shown a second yellow. Abdoulaye Doucoure reduced the deficit with a sweet half-volley.
But Mooy blasted in his second, and Huddersfield’s fourth, from the penalty spot to secure a well-deserved three points.
“We pressed them high, on the front foot, went in their face, kept their offence quiet and away from our goal,” Wagner said.
“We haven’t scored so many goals in the past and collected so many points so to be so strong mentally to be independent even after we have such a difficult away run, this is something extraordinary.”
The only blot on Huddersfield’s afternoon was Kachunga being carried off on a stretcher in the first half. Wagner said the striker had sustained a knee injury and admitted it looked serious.
Silva, meanwhile, was left to rue his side’s third consecutive defeat and fourth in their last five Premier League games.
Adrian Mariappa slipped to allow Mooy in for Huddersfield’s second and Depoitre’s third came after Jose Holebas failed to clear, with the defender instead going down clutching his face.
“For sure now it is our worst performance in the Premier League [this season],” Silva said.
“We didn’t perform really like we need to. We started the game too slow. For the second and third goals we made mistakes at this level we cannot make. It was a tough afternoon for us.”
Watford’s ineptitude could not be excused but they were unfortunate for the first goal as both Kachunga and his provider Quaner looked offside.
Deeney was also unhappy with his sending off as the striker believed he touched the ball.
“Of course I spoke to Troy, he has spoken with the officials as well,” Silva said.
“He said he touched the ball, that’s what he told me. I think the referee answered him ‘it’s not because you take the ball, it’s because of the speed’.”