The DC United striker is the club’s all-time leading goalscorer, a feat that he achieved in his final season at Old Trafford.
The former England international was part of BT Sport’s punditry team for caretaker boss Ole Gunnar Solskjaer’s first game in charge at Cardiff.
The Red Devils thrashed the Bluebirds 5-1, putting on a breathtaking attacking display as the shackles appeared to come off.
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The manor of the victory was a breath of fresh air for United fans after Tuesday’s sacking of Jose Mourinho.
After the match, Rooney opened up on the Portuguese’s style of management and in particular, one thing that surprised him about working under the 55-year-old.
“The game has changed, you can’t just go in and hammer players,” he said.
“Where the players earn enough money now, you lose the players, you have to go into it in a different way and try and keep the players on your side the best managers know how to do that.
“In my opinion, obviously having been there with him for a year, he didn’t [keep the players on his side].
“That was the one surprise that I had, that his communication with the players wasn’t as much as it could have been.”
As he reaches the tail end of his career, the 33-year-old admitted that he is beginning to think about management.
“I’m currently doing my coaching badges,” he added.
“It’s something I’m passionate about. I want to go into coaching.
“Football is what I know, what I’ve grown up knowing and playing obviously, so I think it would be foolish if I didn’t go into coaching.
“If I’d like to manage Manchester United? Of course. One day that would be an absolute dream move.”
The victory in Wales ensured United closed the gap on the top four.
They are now eight points behind Chelsea, who lost at home to Leicester in one of the weekend’s shock results.