11 years without a title I would call a big failure than a good competition
In general, Dortmund has actually turned into a trophy-free club - they sometimes win the German Cup, but all their significant successes like the Bundesliga title or some kind of Euro Cup are in the past. Sad situation for a top 2 club in Germany. In every other country, the top 2 (and even the top 3) have done significantly better in the last 10 years.In the bundesliga, only bayern munich is the most consistent in defending the bundesliga title because other teams are not able to do much because the depth of their squad is relatively dominated by ordinary players but in the depth of the bayern munich squad they are able to present many quality players.
I also think Dortmund needs more effort to get the next season's trophy because they usually sell their good players. I don't know why the money or the trophies? Dortmund have been waiting for so long for dortmund to get these trophies, but I think they always misuse them, and that is why Bayern Munich always challenges them when it comes to these competitions because bayern always utilize their star players in order to get these titles. I don't know if Dortmund management is not seeing how it goes to them, but they really need to change how they are selling their star players.
However, if Dortmund continues this way, I believe Bayern Munich will be leading all the time, and Dortmund will keep waiting until they change or get new players, since they have already sold them out.