“It’s a picture of the quality and the togetherness we have that everyone who starts and plays from the bench knows their job,” said head coach Wagner.
“We’d like to keep it going, but we can never promise the result. We can only promise fight and a working attitude.”
Huddersfield followed an opening day home win over Brentford with a surprise 2-1 success at title favourites Newcastle and a 1-1 draw at well-fancied Aston Villa, prior to edging out the Tykes.
In all four games, players have come off the bench to score vital goals, with Kasey Palmer, Jack Payne, Michael Hefele and Jonathan Hogg making instant impacts.
Wagner told BBC Radio Leeds: “They normally don’t need time to come into the game, and read the game very well. Four games, four substitutions and four goals from them – and a goal from Jonathan Hogg, which is unbelievable.
“We are very fit and able to change the games in the last 20 minutes. The atmosphere is very good after the Barnsley game.
“We say in Germany ‘only the hard worker has luck’ and against Barnsley we had luck, but if anyone deserves it, then I think it is this squad.”