There will always be negative and positive impacts from every player buying and selling activity, especially great players like Serhou Guirassy because Stuttgart will lose their strength which has helped them perform satisfactorily and Dortmund will get great player to help them recover.
But for Serhou Guirassy future, I really not sure he can achieve brilliant achievements with Dortmund because Dortmund current condition, even though Serhou Guirassy has been there, is not enough to be able to compete with other team, especially in the UCL competition.
Serhou Guirassy should be able to get really decent place so he can have much better career, maybe what I said could happen in the future, Serhou Guirassy will only be sold by Dortmund when they get big profit.
Haha Dortmund is team that can indeed create players with high selling prices and develop in Europe, they only have that talent but they are not able to really create history by producing several prestigious titles.
But I curious about Dortmund next season because they need changes to get back to their best performance so they can at least fight for the Bundesliga title.
They became basically the German Ajax with the way they are going. They got a lot of young players back in the day, and sold many of them and instead of using all those profits to build a team that would dominate the league, they are keeping the team sustainable over long period of time. If they make 100 million profit, and then use all that profit to get some players, then with one bad transfer that doesn't produce good results, they would be back to zero.
But if they sell a player for 100, and buy a 25 million one, they can do that 4 more times, and if one of them goes for good, then they would be fine. So all in all, I think it is quite important to keep the business going the way they have been so far, it's the best way.