Dortmund twice came from behind in a hectic clash, only for Dan-Axel Zagadou's straight red card to hand the initiative back to Hannover.
It is now just one win in five games across all competitions for Dortmund, with Bosz coming under some criticism for his side's defensive lapses, and Zorc was quick to slam the display.
"I am speechless about the performance," he told Bild.
"This was smug and pompous. So you cannot win a game in the Bundesliga this way."
Defender Marcel Schmelzer returned to league action on Saturday following a lengthy injury lay-off, and the Dortmund captain echoed Zorc's views, insisting that the players' attitude is to blame.
"We have to discuss a few things. Such a performance cannot be," Schmelzer told Bild.
"We must improve the attitude! We must all ask ourselves. This was a real setback, we have messed up the table ourselves."