Yup they play so damn good lately.
Dortmund in Bundesliga = Arsenal in EPL
Both play beautiful football,and both
used to win championships in
the past.
But the only difference between them that,this season Borussia are gonna win the Bundesliga

while Arsenal fans will be just celebrating their 3rd position as they did in the last 5 years
Schalke are awful this season.
A mediocre midfield and two strikers who don't move much off the ball is not a good combination.
I think this is the main reason behind their poor performance,the two players really don't suit each other,their attack needs a dynamic FW as both of them are slow and not that type of productive FWs.
As for their Midfield,i agree that it is mediocre,but they are always playing with this type of midfield,that's why i think the problem is in the attack.