Bundesliga Preview: Freiburg v Dortmund
Dortmund - who have finished in the league's top two for the last four seasons - are rock-bottom after a dreadful campaign under Jurgen Klopp.
The close-season departures of Mario Gotze and Robert Lewandowski, both to champions Bayern Munich, have undoubtedly hurt Dortmund - who visit Freiburg on Saturday - as have a string of injuries to key players.
But it is still remarkable that a side containing the likes of Marco Reus, Hummels and Pierre-Emerick Aubameyang sit at the foot of the division.
Their latest defeat came on Wednesday, 1-0 at home to a 10-man Augsburg outfit, and the home fans vented their frustrations at the final whistle.
Hummels and goalkeeper Roman Weidenfeller approached the supporters to talk with them and try to calm tensions, but it was not a pretty sight for a club so used to success in recent years.
"We know that we have 15 games ahead of us, full of fight," Hummels told the club's official website.
"Still people expect from us that we play football, not just fight.
"We know that it [our displays] are 98 per cent defined by our fighting spirit. In the other two per cent we have to get a little more relaxed so, 20 yards from goal, we'll make the right decisions."
Dortmund were rushed around goal on several occasions on Wednesday in a match where Augsburg defender Christoph Jacker was sent off in the 63rd minute for bringing down Aubameyang.
With the numerical advantage, Klopp's side piled on the pressure, but Ciro Immobile missed two good chances late on, while Henrikh Mkhitaryan was denied by an excellent Alex Manninger save.
Ilkay Gundogan returned from a thigh problem in the defeat, but Sebastian Kehl (shoulder) and Sven Bender (knee) remain on the sidelines.
While Dortmund are bottom, victory against Freiburg would see them leapfrog their opponents.
Freiburg are two points clear of Dortmund in 15th and lost 1-0 at third-placed Borussia Monchengladbach on Tuesday.
That result robbed them of the momentum gained in their 4-1 come-from-behind win against Eintracht Frankfurt last week.
New loan signing Nils Petersen scored a hat-trick on that occasion and will be out to stop Dortmund's nine-match winning streak against Freiburg, which included a 3-1 triumph in September. Adrian Ramos, Shinji Kagawa and Aubameyang all scored on that occasion.
Freiburg's last victory against Dortmund came in May 2010, with Papiss Cisse netting twice in a 3-1 success.