The 4-0 win, which also featured a Josh Brownhill goal, took the Robins back into the Sky Bet Championship play-off places, but it was the manner of the victory that most delighted Johnson.
“Some of our football today was very impressive and the game was everything I could have hoped for,” he said. “A lot of work from a lot of people went into getting it on and I am delighted that that work was rewarded.
“I wanted us to get our mojo back, by which I meant the confidence on the ball to play out from the back and produce the football we pride ourselves on.
“The goals resulted from some great moves and I couldn’t have asked for more. I told the players I was prepared to take the blame if errors resulted from the way we tried to play and I think that was important.
“Bobby Reid is having a fantastic season and is still relatively new to his position, so I think there is even more to come from him.”
City took the lead on 13 minutes when Reid played a one-two with Brownhill on the edge of the box and ran through unchallenged to beat Joe Wildsmith.
It was 2-0 on 35 minutes as Reid exchanged passes with Marlon Pack before firing past Wildsmith from a narrower angle.
Wednesday fans were already fearing the worst and their team’s fragile defence was breached again two minutes before the break, Jamie Paterson’s clever flick putting Brownhill in to shoot past the unprotected Wildsmith.
Reid completed his treble from the spot on 62 minutes, sending Wildsmith the wrong way after Joel Pelupessy had needlessly tripped Pack inside the box.
Wednesday boss Jos Luhukay declined to have a go at his players after the game, preferring to heap praise on City.
“They were too strong for us today and had too much quality. You have to give them a lot of credit for the way they played,” he said.
“Their two strikers caused us a lot of problems and we couldn’t handle them in offensive situations. One of them is among the top scorers in our league.
“Sometimes you have to admit that an opponent is stronger than yourselves and that was the case.
“In the first half we didn’t only struggle at the back. When we got possession of the ball we had no solution as to how to use it.
“At half-time we tried to put some confidence back into the players and the second half was better from out point of view.
“But when you are 3-0 up, as they were, you can control the game and they did that well.”