Dortmund under this new manager has find form and momentum back and they have a challenge and that is to play in the champions League which is achievable if the they win all their remaining matches and pray that other results go their way in the teams that are ahead of them on the bundesliga table
I'm not sure if the Dortmund coach has had a positive impact on the team. But I know that Dortmund often experiences an increase like this towards the end of the season, and they also experienced the same thing last season. I will admit that the current coach has a positive impact on Dortmund if they get the same results next season with consistent performance.
Regarding whether Dortmund can finish in the top 4 to get UCL tickets in the next season, it seems that they can. But Frankfurt had to hold a draw against Freiburg and Dortmund very easily got 3 points over Holstein Kiel.