Dortmund's unlikely run to last season's final, where they dominated for much of the match but lost 2-0 to Real Madrid, masked a poor domestic season.
Dortmund finished fifth, 27 points behind unbeaten Bundesliga champions Bayer Leverkusen.
That Leverkusen -- local rivals with a much smaller budget -- were able to break Bayern Munich's 11-year title streak, was particularly frustrating for Dortmund's management.
The result was a summer rebuild, with the club parting ways with Dortmund-born coach Edin Terzic and several regular players.
Dortmund have leaned heavily on local knowledge in their rebuild.
Childhood Dortmund fan Terzic was shown the door, despite having also taken the side to within 90 minutes of a Bundesliga title in 2023 before their Champions League run.
In stepped Nuri Sahin, the former Dortmund, Real Madrid and Liverpool midfielder who came through the club's youth system.
Also out the door were striker Niclas Fuellkrug, loanees Jadon Sancho and Ian Maatsen, along with veterans Marco Reus and Mats Hummels.
Dortmund-born former player Lars Ricken, who scored the winning goal in their 1997 Champions League final win over Juventus, has been made head of the sporting department.
Ricken oversees a team including sporting director Sebastian Kehl, who played 362 games for Dortmund and won three Bundesliga titles, while long-time scout Sven Mislintat, who identified some of the club's biggest stars, has returned.
On the pitch, Guinea striker Serhou Guirassy and Germany centre-back Waldemar Anton joined from Stuttgart, while German internationals Maximilian Beier and Pascal Gross have also signed for the club.
"We analysed the situation well and acted accordingly. Sometimes you have to seize the moment," Kehl told reporters last week.
"We reduced the squad size to give young players more space."
Guirassy scored 28 goals in 28 Bundesliga games for Stuttgart last season but his arrival led to the departure of fan favourite Fuellkrug, who left for Premier League side West Ham.
Kehl said Fuellkrug "started thinking" after the Guirassy transfer, adding: "A better opportunity came up in England.
"It was a win-win. In the end, there were no hard feelings."
'Alpha personalities'
Over the years, Dortmund have sought to replicate the governing structure of German giants Bayern, with long-serving club CEO Hans-Joachim Watzke often making public statements like former Bayern boss Uli Hoeness.
Kehl's appointment under Ricken also mirrors that at Bayern, where board member for sport Max Eberl oversees sporting director Christoph Freund.
"As a big club, Borussia Dortmund need alpha personalities," Kehl said.
"Over the years, there have always been strong figures in these roles. Big clubs need to be led that way.
"It's a new set-up, and there were some changes in the summer. Within this structure, we did very good work over the summer."
Dortmund have seven points from their opening three games of the Bundesliga season.
While the players were content to sit deep and counter-attack under Terzic, Friday's 4-2 win over Heidenheim showed Sahin's possession-based approach is already starting to bear fruit.
The first European test comes at Belgian champions Club Brugge.
Although Dortmund will always be judged on their domestic performances first and foremost, the Champions League run led to the club's biggest ever annual revenue -- crucial for a side dependent on European income to compete on all fronts.
