The next match for Stuttgart will be against Darmstadt in Bundesliga and we know a team like Darmstadt can't make trouble for Stuttgart. Currently, in the past games we saw from both teams, Darmstadt is a team in 17th place in the table which can be the reason to say they didn't have a good performance so far and are not in the situation to beat a team like Stuttgart. On the other hand, as you said Stuttgart is currently in a good situation and they start the reason better than we were expecting to see from them.
When I thought a team like Darmstadt couldn't make trouble for a team like M'Gladbach I found the opposite happening. The draw between these two teams was unexpected for me and both scored 3 goals was impressive. M'Gladbach were playing vs 10 players that helped them securing the draw, otherwise they might lost the game.
Well it is true M'Gladbach isn't that good anymore as I see while Stuttgart are doing good in Bundesliga this season. That's to say that Darmstadt and Stuttgart match might be tricky although the advantage that Stuttgart seems to have.