The 42-year-old watched his Schalke side concede four times in 37 second-half minutes on Saturday, with Robin Knoche breaking the deadlock. The young defender got on the end of a header into the box from Ivan Perisic to score after 54 minutes.
Vieirinha and Naldo got in on the act before Stefan Kutschke completed the scoring by marking his debut with a goal, sending the ball through Timo Hildebrand's legs to add insult to injury.
"I don't want to get it out of their heads right now (the reason for the poor performance). We have to work through it. That's important. We will analyse the mistakes we made," he insisted.
"But as I said, I can't just forget this result. There were too many mistakes from the 54th minute on, after we went 1-0 down. We made too many mistakes.
"We have league and cup weeks in front of us. It's not like I am punishing them. They understand it."
