Head coach Niko Kovac used the emphatic win to underline his confidence in the squad's depth and leadership as they gear up for the Bundesliga.
The goals came from a spread of talent, showcasing Dortmund's firepower: Elias Benkara (13'), Yan Couto (16'), Marcel Sabitzer (25'), Karim Adeyemi (28'), Julian Brandt (36', 37'), Maximilian Beier (66'), and Ayman Azhil (71').
The clinical display, as noted in Dortmund's official X post, highlighted their "ruthless finishing" against the lower-tier side.
Sky Germany's Patrick Berger, a reliable voice on Dortmund, reported that the club are unlikely to sign a holding midfielder this summer.
"We are looking and observing everything, but we are not targeting a player in that position," Kovac said, dismissing transfer rumours.
The 53-year-old also reaffirmed the leadership trio of captain Emre Can, vice-captain Julian Brandt, and Nico Schlotterbeck. "There are no reasons to change anything. I am satisfied with the choice my predecessors made," Kovac stated.
Can, 31, has led the side since taking the armband from Marco Reus in July 2023.
With their X account buzzing about the Siegen rout, Dortmund are clearly building momentum. Kovac's faith in his current roster and the squad's dynamic performance suggest they are poised for a strong season.