Neither the signing of Jude Bellingham nor Borussia Dortmund's transfer policy have been well-kept secrets. The 17-year-old midfielder finally put pen to paper on a "long-term" deal that set Dortmund back about €23 million ($26 million) on Monday, in a further confirmation of the club's desire to sign young and, eventually, sell high.

"He has enormous potential, which we will continue to develop together with him over the coming years," said Dortmund’s sporting director, Michael Zorc. "He already boasts astonishing quality with and without the ball, and has a strong mentality to boot. Jude will immediately strengthen our first team squad, but we will certainly give him all the time he needs to adapt to the higher level of play."

The former Birmingham City player becomes the latest in a long line of teenage talent signed by BVB with an eye to development, short-term sporting gain and long-term financial windfalls. Ousmane Dembele, Christian Pulisic, Gio Reyna, Jadon Sancho and Erling Haaland are recent examples of the strategy.  

The last two have not yet left the production line, though Sancho's future is a constant source of speculation. Whether he leaves or not, there's no doubt the €8 million Dortmund paid Manchester City for an unproven 17-year-old on the last day of the summer transfer window in 2017 has been a spectacular success. 

While the two players moved to Germany at the same age and from the same country, that's where their stories diverge. Sancho arrived having never played for City's first team whereas Bellingham has been one of second-tier Birmingham's key players this season, after becoming the club's youngest debutant at the age of 16 years and 38 days last August. 

 A complete midfielder

After scoring in only his second substitute appearance in the Championship, he hit the target again when making his first start. But Dortmund fans shouldn't expect someone who'll reach the kind of goal and assist tallies of Sancho. Bellingham is most often used by Birmingham as a deep-lying central midfielder but has also played on the left and right of midfield, just behind the striker and even up front. That versatility will serve him well when he tries to break in to Dortmund's first team.

But the coach who gave him his first team break thinks the base of midfield is where his future lies.

"For me, that's Jude's best position playing in midfield in front of the back four," Pep Clotet, who recently left the club, told Birmingham City's official website. "When he made his debut here at St. Andrew's he did it on the wing... so he had to come in and try to link in behind, but in my head, he was always a midfielder. He can go forward as well, he can defend, he is very complete and despite being only 16 he handles the physicality of the midfield very well."

While England's second tier is competetive, and physically demanding, the Bundesliga is a siginificant step up in quality and intensity. But Bellingham's quick feet and quick mind should help him cope with the pressing favored by many German sides.

The right place

His ability on the ball, maturity and physical prowess meant it wasn't just Dortmund that were interested in Bellingham, with Manchester United and a host of other top European clubs also said to have made enquiries. But the club's proven recent record of developing talent swung it for the youngster.

"I’m incredibly excited to have joined one of the biggest clubs in Europe. The direction they are heading in and how much they help young players improve made it an easy decision for me personally and my family," he said. "I can’t wait to perform in front of over 80,000 fans when they are back inside one of the most beautiful stadiums in the world – hopefully as soon as possible!”

In the strange fashion that has become familiar in recent years, Dortmund fans will be hoping Bellingham can make the most of any early opportunities but also that he's not so good that they lose him too soon. But that's for the future, for now Jude Bellingham is a Borussia Dortmund player.