A stunning double from Adam Reach and goals for Julian Borner, Callum Paterson and Jordan Rhodes did the damage for the Owls, who suddenly have a skip in their step having started the match at the bottom of the Championship table.
And while the scale of the result came as a surprise to Wednesday assistant manager Jamie Smith standing in for Darren Moore who is still out after his positive coronavirus test late last week, the performance was no shock at all, he said.
Asked whether he expected the sort of emphatic result, former Crystal Palace player Smith said: “Not 5-0, no, not against a top team like Cardiff. But we know we have quality within the group and we know a performance like that is there and it’s about bringing it out more often.
“It’s not surprise to us as staff because we sit there, we work closely with these players in training sessions and we see that quality day-in, day-out.
“All five of them were fantastic goals, but it’s not surprise, we see it every day.”
The win puts Wednesday within six points of fourth-bottom Birmingham City with seven matches left to play.
On a Bannan display described by one pundit as the best in the second tier this season, Smith said: “Baz has incredible quality and abilities as a footballer, but the team as a whole, everybody from one to 11 and the subs that came on as well, it was a real team performance and a club performance.
“It’s definitely not too little too late. There’s still time, there’s still seven games left and we’ll be out there fighting for every point that’s available.
“Every game we play we always sit down and look back on it, good and bad, every game is the same and this will be no different.
“I’ve spoken to Darren,” Smith said on a manager he’s worked with for nearly a decade. “He’s feeling a little bit better, put it that way! He’s really pleased with the performance.”