Dortmund knew not to expect immediate perfection. Its chief executive, Hans-Joachim Watzke, had accepted there would be “one setback or another” along the way, but, like others at the club, he deemed the occasional low a price worth paying for a high that promises to be exhilarating.

The new arrivals, after all, are not Dortmund’s only tantalizing prospects. Julian Weigl, a 20-year-old midfielder who came from Germany’s second division, has made the national team. Erik Durm and Matthias Ginter were both on the Germany squad that won the 2014 World Cup, and Barcelona and Liverpool are among the teams reportedly keeping a close eye on the American teenager Christian Pulisic.

Seeing so many players Dembélé’s age thrive at Dortmund not only convinced him that the Ruhr valley was the best place to nurture his career, but it also has turned the club into soccer’s premier destination for young talent. It is a reputation that fires considerable pride, but Zorc acknowledged it was as much an economic necessity as a philosophical preference.

“It is not our primary goal to have the youngest squad among Europe’s top teams,” he said. “We are not on the same level in terms of money as, say, the eight best teams in the world. We cannot solely buy ready-made stars. We also have to develop talent, and we have proven in the past that we can offer even very young players the chance to play at the highest level.”

As the chase for Dembélé illustrated, though, competition for soccer’s brightest prospects is intense. In that context, what sets Dortmund apart is not only identifying them so reliably but enticing them so consistently.