Well, I don't think Drmic falls in the category of Ronaldo and Ronaldinho at all. Those two were coming from Brazil trying to get a foothold in Europe. Drmic is a starter in a major European league already.
In fact, I think it is closer to the truth to compare Drmic to the point where Ronaldo and Ronaldinho were at when they decided to leave PSV and PSG respectively. If Drmic chooses Leverkusen now, I see it as a lack of ambition and a lack of belief in his own abilities. If that is the case, then he was never the player for us.