Four months on, the sight of Wayne Rooney in a Derby County tracksuit is still slightly surreal. Even more so given he is discussing tackling Manchester United on Thursday, emitting a warm glow as he tries to sum up more than a decade at Old Trafford: 13 years, 12 trophies, 559 appearances and a record 253 goals. “I loved it there,” he says. “Some huge highs and some lows. When you’ve been somewhere so long, and you look back on it, your old teammates and the staff, it was the main part of my career. It was enjoyable and something I’ll look back on with great memories. There was obviously the time when I nearly left the club, which I regret. There were lows but they were certainly outweighed by the highs.”

For Rooney the FA Cup fifth round promises to be a special, if not a slightly strange occasion at a sold-out Pride Park but facing United is not an alien prospect after twice doing so on his return to Everton three years ago. By the end of the 2017-18 season, Everton deemed Rooney dispensable and he left for DC United until touching down at Derby. The muddiness of that second Goodison Park exit rankles. “It was a big thing for me to go back there. There were things that got said, or didn’t get said. At the end of the day all I wanted from Everton was a bit of honesty with the situation. I said to them: ‘I’m not a child, I’ll accept whatever you want to happen here.’ That was the only disappointment. But Everton is a fantastic club, I’m delighted for them bringing [Carlo] Ancelotti in and they look like they are thankfully, finally, moving forward.”

Rooney has a greying, bushy beard but, as he details his evolution into a quarterback, he conveys the same earthy enthusiasm he had as a kid at Everton, be it striding forward with the ball against Leeds despite losing his right boot on halfway or thinking on his feet as a 14-year-old in the under-19s. “Physically, it is easier. I think some people think playing midfield is more demanding but it is more about having the endurance, there is not as much high-speed running, so that is not a problem,” the captain says, with a wry smile. “Then it is about trying to get on the ball and trying to drag players out of position. A lot of the games teams try to put players on me – they have in a few of the games – which allows me to drag them out of position and leave space for Tom Lawrence, Jason Knight, Duane Holmes or whoever comes into that space.”

Rooney’s role may have altered but his hunger has not diminished. Since his Derby debut in January, the 34-year-old has completed 90 minutes on all but one occasion, when withdrawn with Phillip Cocu’s side 4-0 up against Stoke, and has had a positive impact on the squad, notably the 19-year-olds Knight and Max Bird, who Rooney believes should be considered by England in the coming years, but his influence does not stop there. Rooney is a player-coach and spent December, while ineligible to play, watching Cocu at close quarters, immersed in the world of pre-match preparation.

Wayne Rooney says playing in midfield is physically easier: ‘There is not as much high-speed running.’ Photograph: Nick Potts/PA

“You sometimes make a suggestion on players, on how we should play, or a set piece and you’re thinking: ‘I hope it pays off!’” he says, breaking into laughter. “He [Phillip] is open to that [input], of course, with all the staff. I think the best managers do. You can’t be naive and think: ‘I’m going to do it all my own way.’ Phillip has obviously got a team around him where we all try to help him but of course the final decision is his.”

This summer Rooney, who has designs on being a manager, will complete his Uefa A licence before applying for the pro licence. After matches his ritual remains the same: he returns home to the north-west and sifts through the game. “I’ve done that since I was a kid,” he says, but his dual role has meant subtle changes. For example, on matchday Rooney arrives earlier than the rest of the players to finalise tactics with Cocu and his staff and, last Sunday, he spent the afternoon making notes on United’s visit to Goodison Park, assessing their weaknesses and vulnerabilities.

“I can’t play forever so I need to think about my future after my playing days. I love the game, I want to stay in it, so this is where I am and I want to learn as much as I can. I think it’s a shame when you see players who have been great players walking away and not really having a go at managing or coaching. Over the last few years it’s been great to see Frank [Lampard], Steven [Gerrard], JT [John Terry], Scott Parker, to see all of these former teammates of mine going into it.”

In Sir Alex Ferguson, Rooney had a priceless education. “His man-management is the best I’ve ever seen. I always remember as a kid, every half-time arguing with him. Constantly. I remember thinking: ‘Why’s he keep having a go at me? There’s players far worse than what I’ve been.’ But the older you get, you realise why he’s doing it. He would have a go at me for dribbling, which I very rarely … well, I dribbled a bit more then,” he says, smiling. “But for [players such as] Nani, it would just maybe trigger something in their head, make them think: ‘Maybe I shouldn’t dribble as much.’ If he [Sir Alex] spoke to Nani the way he spoke to me, he’d break down in tears. He [Nani] wouldn’t be able to come back out.”

Wayne Rooney celebrates one of his record 253 goals for Manchester United. Photograph: Tom Jenkins/The Guardian

From an unforgettable hat-trick on debut against Fenerbahce to his farewell appearance in the Europa League final in Stockholm three years ago, Rooney is better qualified than most to take United’s temperature. “The important thing is for them to try and get into the Champions League this year. It is really tight at the minute. I think that will help them a lot if they can do that, but it is going to take time. It is going to take another two or three years, I believe. The Manchester United fans need to be a bit patient with what is going on and let these players try and prove themselves. They need to bring some players, they need to get rid of some players, also, I think, and within two or three years they have to be challenging again. Over the last few weeks they have been getting better, it will be nice to see them bring in two or three players in the summer and try and make that next step to get a bit closer.”

As Rooney acknowledges, there is no quick fix to restore United to Europe’s top table. “They’ve tried that with Van Gaal, with Mourinho. If you look at Liverpool and what they’ve done, and Man City, you’re not going to buy a team to go and challenge with them. You see with Liverpool – they’ve built that team. Guardiola has gradually brought more players in and [has] his way of playing, so United have to be a bit patient and try and build a team that will be able to challenge those two.”