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.
I fully agree on that , that Füllkrug was playing very good at the time he was in Dortmund specially in the Champions League.
Getting a bit of money back for him is and was a bonus and also was the step to invest the money back into Beier.
Lets see if Dortmund will be selling him in a few years , but i guess it will take some more years before they doing this if they doing it.