That result left Bremen nervously looking over their shoulders at the battle for survival rather than challenging for a place in Europe, and while Schaaf says he never expected it to be an easy season, he had not quite imagined it being so difficult.
"We've got to be realistic and we knew what kind of a season we were going to be up against, but certainly we had not planned on this today [Saturday] or the defeat in Munich," he said.
"They should not happen either, but we are really struggling right now.
"We put the effort in, but we just weren't united enough."
Bremen midfielder Zlatko Junuzovic said the time has come for the team to regain their focus and let their actions speak louder than words.
"That's enough talking," he said. "So much discussion goes on here, but we need to concentrate on our performances and ensure that we get back to playing normal football like in the first half of the season.
"We need to bring the enjoyment and the pleasure back into our football. We are making our lives difficult for ourselves."
And the club's new director of sport Thomas Eichin expressed his disappointment at an abject performance which he did not expect to see from such players.
"We have players here who have higher expectations of themselves," he said. "They have now got to show this on the pitch.
"We must play differently to this in a home game. Everybody has got to ask themselves questions."
The defeat left Bremen just seven points above their opponents, who currently occupy the relegation play-off berth.