The scene was a meeting room in a plush Istanbul hotel. The president of a high-flying Turkish football club sat on one side of the table crunching the numbers while David Moss, the agent charged with negotiating his client’s personal terms, allowed himself a moment of self-reflection. “It was fascinating watching it all play out, the negotiations on fees and pitch on salary packages,” he said. “I found myself smiling a lot of the time because I know how it works. The club know what they can pay and what they can’t even before everyone gets round that table. It’s all a game. But a game I can now see from all angles.”

Moss is in an almost unique position when it comes to the forthcoming transfer window, having filled virtually every role going in football’s recruitment business over a lengthy and diverse career. He has been the player, the nomadic midfielder crisscrossing the lower leagues from Doncaster Rovers to Chesterfield, Falkirk to Partick Thistle. He has spent time in youth football as academy manager at Swansea City and Crystal Palace, then seven years at Celtic which eventually saw him oversee their senior scouting division. At the end of last season he left Celtic Park to become head of football operations at Huddersfield Town, newly promoted to the Premier League, and directed a frantic summer of squad strengthening.

Then came an abrupt departure from the John Smith’s Stadium in late autumn and now, armed with a masters in sporting directorship from Manchester Metropolitan University and a place on the Football Association’s recently created level five course for technical directors, he is an agent working informally with Mitem Sports. These are early days wearing his latest hat, and the reasons for his sudden if amicable divorce from Town are bound to secrecy by a confidentiality agreement, but clubs and players alike will see the value in tapping in to his vast knowledge when it comes to the scramble to strengthen or balance the books.

“As a sporting director I helped players play in the Premier League, and I could see the excitement in their eyes at signing for a top-flight club,” he said. “I’ve seen ‘little Huddersfield’ spend £11m on Steve Mounié, £7m on Aaron Mooy, £8m on Tom Ince, the kind of fees they’d never paid before, and I’ve seen the excitement, too, on the owner’s face. Now I’m in a position where I can help clubs sign players they might otherwise not have known about through the contacts I’ve built up. I can source players outside their normal channels, and help players from abroad find a way to play in England.

“Leaving Huddersfield came out of the blue but, in life, things happen which throw you in a different direction. At Palace I’d overseen an academy producing the likes of Victor Moses, Wilfried Zaha and Nathaniel Clyne under Simon Jordan’s ownership. I was on a cross-Channel ferry back in 2010 going over to Holland with an under‑16s team when the managing director, Phil Alexander, rang to say we’d gone into administration. I was one of 29 people who’d been made redundant. The sense of shock … but over the next few months I had the head of youth development at Celtic [Chris McCart] calling me up to head up the scouting for their academy. I eventually gave in, and it was the best decision I ever made. That role submerged me in scouting, from youth into senior level, and set me up for everything.”

Life at Celtic, “a juggernaut of a football club”, was a challenge in a market warped by English Premier League clubs’ turnovers. Where English top-flight clubs would receive £100m per season at the very least through broadcast rights, Celtic would be all‑conquering domestically on around £2m a year in television revenues, but Moss and his staff – half-a-dozen full‑time scouts in Scotland and England, and seven or eight assigned to regions in Europe – would still have to recruit players capable of holding their own in the Champions League. “The most we could pay would be around £3m, and we had two criteria: did the player have the ability and character to compete against the likes of Barcelona, Paris Saint-Germain, Manchester City, AC Milan? And did they have the potential to be sold at a huge profit?

“Victor Wanyama, Fraser Forster, Virgil van Dijk, Moussa Dembélé – all had that huge potential. The big clubs all knew about them but found faults and reasons not to pursue them. If you’re receiving £100m every year, why take risks? You can wait for a club like Celtic to do that and if you have to pay through the nose further down the line for the finished article, so be it. But you can see a Rolls Royce of a player early. I used to say to Premier League clubs: ‘Van Dijk is a man playing in a playground against kids, he stands out so much. He’s 6ft 4in, can ping it from one end of the field to the other, can head it, scores goals, is quick … he’s got everything.’ And they’d still go and buy someone else. I’d despair.

Look at what Les Reed has achieved at Southampton: there is the example of the system working perfectly.

“I was aware of Dembélé when he came over to Fulham from PSG, and all the Premier League clubs had watched him in the Championship. He wasn’t the quickest – he’s not slow, either – but he’s got great presence, is a natural finisher, and has a big-game mentality. The bigger the game, the cooler he is. Once it was clear he wasn’t going to sign a new contract at Fulham, that deal was perfect for us. English clubs would have to go to a tribunal and pay up to £5m for him, but Scotland is considered ‘cross‑border’ so we only had to pay £400,000 in compensation. He’s only 21 and is a dark horse to go with France to the World Cup. The bigger the game, the bigger his contribution. I’ve seen the suggestions he might go for £18m this window, but he’d still be cheap at £30m.”

As head of scouting, Moss would spend the vast majority of his time traipsing across Europe, or south to the Championship or below, with the manager’s positional wish-list always in mind. Brendan Rodgers would call monthly meetings where the Yorkshireman would present the department’s findings to the manager and his staff. “Say we were looking for a box-to-box midfielder, we’d deliver 15 different options and Brendan, very professional, would make notes on each player. We’d go into each one, their strong points, and whittle it down to an absolute maximum of four to focus on. Brendan would say which ones he preferred, and we’d get the go-ahead to explore how much it would cost us, either with the agent or the club.

“Initially, you’re looking at technical and physical abilities, then tactical and football intelligence, such as positioning. And then you’d have his psychological profiling, talking to people in the game or around the player. Further down the road we could come together again and update, and then hand over to the chief executive, Peter Lawwell, and [the company secretary] Michael Nicholson to deal with the financials with the player’s agent once we had permission from his club. That process eventually landed us, say, Olivier Ntcham, from Manchester City, who we’d watched [on loan] at Genoa.”

Seeing these success stories play out at Parkhead provided satisfaction for Moss, but he craved authority over the whole process. When Huddersfield targeted him to replace the departing Stuart Webber, even Rodgers told him he would be mad not to accept. Town had been promoted on an £11m budget, one of the lowest in the Championship, with their new head of football operations inheriting two full-time scouts. Some of Moss’s staff at Celtic followed him south and a network sprang up across Europe almost overnight, alongside new data, video scouting and analysis staff. The owner, Dean Hoyle, embraced progress, and the manager, David Wagner, pushed for recruitment to be implemented swiftly and efficiently. The results were eye-catching.

Steve Mounié, one of David Moss’s key recruits for Huddersfield, celebrates scoring against Brighton in December. Photograph: Oli Scarff/AFP/Getty Images

Moss, working from Town’s near‑deserted training ground over the summer, and Wagner spoke two or three times a day and the owner backed the pair’s judgment. It was a slick operation, aimed at securing “the best players within our budget”, and 14 had signed up even as top‑flight rivals were still sifting through their own lists of prospective targets. “It was fantastically exciting and I secured players I’d liked at Celtic but could never afford,” Moss said. “Celtic ran an amazing business, but we’d stumble as soon as the fees rose to £4m, or the player wanted £2,000 extra a week. There is more leeway down here even at a newly promoted team.

“The Mounié deal was a big one, £11m up front and potentially £13m to Montpellier, but to be there at Palace on the opening day of the season – you know all the work that’s gone in behind the scenes to make that happen, and then your record signing goes and scores two goals to give you a flying start. It’s unfortunate he’s had an injury since, but Laurent Depoitre was another we’d tried for at Celtic. He’d made the wrong move by leaving Gent for Porto for £6m: he’s not a Latin-type player. He’s made for English or German football, so his value had gone down since to a bargain €2.5m.

“That can be the best time to buy. Anyone can spot a player who’s man of the match every week. It’s when you’ve seen their potential and yet they’ve slipped – confidence, injury, out of favour – that you have to move. Laurent’s another big lad, 6ft 4in, and not the prettiest on the eye in training, and David would come to me saying: ‘What have you bought here?’ He was off the pace in training, but he comes alive on matchday. David took some convincing to play him against Leicester [in September] when Mounié was out, but he bullied Harry Maguire and was the best player on the pitch.”

Recruitment was only one aspect of the job he had taken on in West Yorkshire. Moss has long been an advocate of the sporting director role, pointing to the benefits of a figure to implement the board of directors’ vision. He can dictate the wider strategy, ensuring the best people lead each department, and provide continuity, some long-term planning (from contract negotiations to scouting) and a point of reference for all at the club. He had been joined on the two‑year Manchester Metropolitan course by Michael Appleton, Steve Round, Sean O’Driscoll, Ashley Giles and prominent figures from the worlds of rugby union and Formula One. The creation of the FA’s level five 18-month course, whose inaugural intake will begin work at St George’s Park in February, recognises the growing trend of clubs following the European model and it has enlisted Moss among its initial batch of 12 students.

Many of those, from Dougie Freedman at Palace to Richard Hughes at Bournemouth, are already employed as technical directors in the Premier League or general managers at Women’s Super League clubs. Dan Ashworth, formerly in the role at West Bromwich Albion and now at the FA, had long been keen to run such an initiative with similar courses already established to assist scouts and recruitment staff. Senior leaders from business and other sports will lecture the students, and there will be a study trip to Munich to scrutinise the successful German model.

“If you don’t have that figure implementing the club’s vision, people can start shooting in different directions, politics kick in, and potential is passed up,” Moss said. “Look at what Les Reed has achieved at Southampton: there is the example of the system working perfectly in this country, and everyone knows what Southampton are about. In England, there have been a lot of bad appointments with the wrong people put in these positions, and that has put clubs off the idea. But get the right person in the job and the benefits are obvious.”

At some stage, his own career will surely take him back into a role he enjoyed too briefly at Huddersfield. He boasts all the credentials and contacts to fill the void left by Michael Emenalo at Chelsea. But for now, he is working with the technical directors in situ to place his clients in the transfer window to come. A frantic month awaits.