Why Barcelonas Karim Adeyemi transfer is unlike any Borussia Dortmund sale in yearsBarcelonas signing of Karim Adeyemi has not only strengthened Hansi Flicks attack but also brought an end to one of Borussia Dortmunds most consistent transfer trends.The German winger arrived at Barcelona in a deal worth a fixed 22 million, with a further 7 million in performance-related add-ons.While the agreement certainly represents a sensible piece of business for Borussia Dortmund given that Adeyemi had entered the final year of his contract, it falls well short of the enormous profits the Bundesliga side has become famous for generating in the transfer market.According to the figures involved, Barcelonas Karim Adeyemi transfer is one of the few major Dortmund departures in recent years that has not resulted in a substantial financial windfall for the German club.Adeyemi transfer bucks Dortmunds transfer modelBorussia Dortmund signed Adeyemi from RB Salzburg in 2022 for 30 million, viewing the German international as another exciting young talent capable of developing into a world-class player.Four seasons later, however, Barcelona secured the winger for a package that could reach 29 million, meaning Dortmund were unable to sell the player for more than they originally invested.That is a rare outcome for a club that has built a reputation for identifying young stars, developing them and eventually selling them for enormous profits.A look at Dortmunds blockbuster salesSome of Borussia Dortmunds most successful sales have involved Spains two biggest clubs.The most famous came in 2017, when Barcelona signed Ousmane Dembele in a deal worth 135 million including bonuses.Dortmund had paid Rennes just 15 million a year earlier, allowing them to generate an extraordinary profit of around 120 million.Karin Adeyemi signed for Barcelona for just 22 million. (Picture credit: X/@FCBarcelona)Later, in 2023, Real Madrid completed the signing of Jude Bellingham after Dortmund had developed the England international into one of Europes finest midfielders.Having signed him from Birmingham City for 29 million in 2020, Dortmund sold him to the Spanish giants in 2023 for 127 million.The club also enjoyed huge returns on players such as Jadon Sancho, Christian Pulisic, Erling Haaland, Pierre-Emerick Aubameyang, Henrikh Mkhitaryan, Mario Gtze and Jamie Gittens, reinforcing their reputation as one of world footballs smartest clubs in the transfer market.Against that backdrop, the Adeyemi deal stands out as an exception rather than the rule.