Stöger arrived from Cologne, about a 75-minute drive to Dortmund, a week after getting fired because last-place FC Cologne failed to post a win in its first 14 Bundesliga games -- the worst start by a team in Bundesliga history.
His recent run, obviously, is not what made him appealing.
"He did outstanding work in Cologne over four [and a half] years and steadily evolved the club," said Borussia Dortmund director Michael Zorc. "His team established great stability, and it's stability that we hope to get from Peter."
After one day of practice with his new team, Stöger celebrated his first Bundesliga win since last May. Borussia Dortmund beat Mainz, 2-0, on Tuesday, ending an eight-game Bundesliga winless streak.
Stöger had arrived at then second division Cologne from Austria Wien in 2013 and guided the Billy Goats back to the first division with a first-place finish. In his first two seasons at the top flight, they finished 12th place and eighth -- and its fifth-place finish last season earned them a Europa League spot, FC Cologne's return to European competition after a 25-year absence.
He remained popular in Cologne despite the horrible run this season and received a standing ovation good-bye after his last-game in charge, a 2-2 tie with Schalke 04.
Why Bosz got canned: The Dutchman, a Johan Cruyff disciple, had led a young Ajax Amsterdam team to the 2017 Europa League final, where it lost 2-0 to Manchester United. BVB paid Ajax more than $5 million to buy out Bosz's contract -- although he had never won a major title -- and in the beginning it looked it may have been a good deal.
BVB had its best start to a season in club history and led the Bundesliga by five points after seven games. But the collapse was dramatic.
In its last 13 competitive games, BVB's only win came in a 5-0 German Cup victory over third division Magdeburg. It dropped to eighth place in the Bundesliga and was eliminated from the UEFA Champions League with two ties and four loses, a year after having reached the UCL quarterfinals.
The 51-year-old Stoeger had been on BVB's short list to replace Tuchel, and clearly Dortmund believes Stoeger's horrific run this season is excusable: Cologne loaned Frenchman Anthony Modeste, who scored 25 goals last season, to Chinese Super League club Tianjin Quanjian and had major injury issues.
While Cologne is destined to drop to the second division, Stoeger has a contract through the end of the season with BVB, which was 12 points behind league leader Bayern Munich and three points below the Champions League qualifying zone when Bosz got the sack.
Dortmund's third-place Champions League group finish sends it into the Europa League knockout stage, and Stoeger will become the first man to coach two different teams in the same Europa League season. (Cologne was eliminated with a third-place finish in Group H, from which Arsenal and Red Star Belgrade advanced.)
Stoeger's achievements: A midfielder, he played 65 appearances for Austria, scoring 15 goals, and retired at age 38. He won three Austrian titles with Austria Wien and finished UEFA Cup Winners' Cup runner-up with Rapid Wien.
He won the Austria Cup in his first season as coach in 2005 with Austria Wien and lifted the 2012-13 league title after returning to Austria Wien following stints at First Vienna, Grazer AK and SC Wiener Neustadt.
BVB's faith in Stöger -- "I don't think they came calling because of what I've done the last few weeks," he said at his introductory press conference -- stems from what he achieved last season.
"If you finish fifth place with FC Cologne," said BVB CEO Hans-Joachim Watzke, "that's like winning the championship with one or two of the big clubs."