Füllkrug played very well in Dortmund last year in my opinion. Dortmund made a good profit by selling him for a good transfer fee. Now they bought young Beier instead and will sell him for a higher price. If he shines well for a year or two, Beier can earn Dortmund big money. Guirassy will give the impression of being the other goal scorer.
Dortmund have always been able to do business like that every season so it is not surprising that they continue to do things like that to get more money. Because in general Dortmund have always been able to turn ordinary players into expensive players by honing and training them well before selling them for a fairly high price. But the focus at the moment is actually about Dortmund who could be a threat to other teams in terms of winning the Bundesliga trophy because Dortmund already has Guirassy as a player who will score goals for the team's victory.