A standard story for Dortmund - after a series of bad games there is a series of good ones and vice versa, many at the moment think that finally serious changes have occurred, but no. Last season, Dortmund showed phenomenal results after the change of coach and they were able to rise from the depths to the Champions League zone, but now I see all the same signs of instability. Sometimes I think that if you correctly guess when Dortmund starts a bad streak (or vice versa, a win streak), then betting on them you can become a millionaire 
But at the start of next season I will just wait first and if there are no signs of obvious progress I will throw them out of my cash bets for the season, last season I burned a lot of multi-bets because of them.