Nothing wrong with getting some transfers wrong anyway, you take it on the chin and move on is the more important part. Sometimes there's nothing you can do about a signing not working out, talent and fitness are often enough there but climate, getting accustomed to life in a different country mental application etc are factors you usually can't fully account for.
Sahin is a good example, made his debut as a 15 year old generational talent but injuries and other issues stunted his development. Turan went from the hardest working creative midfielder around to a lazy piece of shit within weeks of his transfer, also didn't help that he went insane and into a hospital to hand his love rival a gun telling him to shoot him as an apology π