Dortmund is the only german club that did something significant in European cups and then "kind of" stayed close to the top, competing with best teams (except Bayern of course).Rest of the Bundesliga clubs is just a history of one-season wonders followed by selling your best guys. Dortmund also sells but we somehow manage to find strong replacements for the most part at least.
In recent decade we had Bremen in 2009 reaching the UEFA Cup final, Schalke played in CL semis in 2011 I believe, then we had Dortmund in CL final in 2013. In 2016 Wolfsburg almost knocked-out Real in the quarterfinals. Now we had Frankfurt in Europa League semis. Maybe I'm forgetting someone as well. But it always ended the same. It is a bit sad that no club other than Dortmund and Bayern seems to be growing over the years, like they have no long-term plan to actually build something. Maybe Leipzig will change that trend.
And Leverkusen is a weird case because they almost always seem to be strong enough to reach the CL group stages or Europa League but they never develop into something more, but also never collapse.
