Dortmund has not been playing good in any of the competitions. They got punished in the DFB Pokal and were kicked out against Stuttgart and that game revealed all the weaknesses Dortmund is dealing with. The Bundesliga is again revealing everything as they are just not as lucky all the time as they have been in the Champions League. I don't know how often it happened that a team qualified for the next round in the CL when they scored only 7 goals in 6 games and were in one of the strongest groups of this season. Dortmund has played several games they should have lost, but didn't because their opponents were too stupid to score. I doubt that they will stay in the CL for two more rounds. Eindhoven is still doable for them, but I doubt it will be a long adventure for them.
In fact, Dortmund is already 6 points behind Leipzig who are in the top 4. This is quite a drastic decline in their game this season because in previous seasons we saw that Dortmund always managed to stick closely to the top of the standings, but this they are relatively weaker. I think this season from what I've seen they haven't been able to balance their game as well as they could and some players have really found it difficult to develop their best qualities. Well, losing Bellingham has had quite a big impact on them this season because their front line is not as aggressive as last season in terms of scoring goals.
Terzic has a more difficult job this season because they really have to work hard to get back into the top rankings. Terzic must also be able to bring changes for the second half of the season and he must be able to see the weak points in his team that can be fixed in this winter transfer window. If they can't change their performance in the second half of the season, of course this season will be a pretty bad season for their performance in the Bundesliga.
That's how I see it, yes. They are falling behind like they haven't been falling behind in a long time. However, I think it also has to do with the flawless season that Leverkusen is playing. If you have one club playing the perfect season, everyone else is looking worse for obvious reasons. But still this isn't just looking bad for Dortmund because Leverkusen is playing well. It is looking bad for Dortmund because they are playing crap. It is just bad. It is weak and they should have lost more games than they actually did because they sometimes got lucky, which makes it even worse given where they are at in the table. The weirdest thing is that they qualified for the round of 16 in the Champions League. I guess that is what saved Terzic the job until now.