Schalke star Julian Draxler labelled Sunday's defeat to Cologne as "one of our worst performances in recent years" as pressure mounts on coach Roberto Di Matteo.
The former Italy international led Schalke to five consecutive home wins in the league after replacing Jens Keller in October, and they sat well in the race for a UEFA Champions League spot at the mid-season break.
However, the Gelsenkirchen club have won just four times domestically since the campaign's resumption and are currently clinging onto a Europa League spot in sixth with Borussia Dortmund and Werder Bremen ready to pounce below.
Falling 2-0 at Cologne secured the hosts' top-flight safety in their first season back in the Bundesliga but left Schalke 13 points behind fourth-place Bayer Leverkusen.
Draxler said: "We played really badly. I don't know what was wrong with us. You're not going to win games in the Bundesliga like that.
"I'm pretty sure it was one of our worst performances in recent years.
"We're also aware of the anger of our fans. They have reason to be unhappy and vent their anger. Having said that, we have to get through what's been a poor season together."
Schalke captain Benedikt Howedes was at a loss to explain the Cologne capitulation and his side's generally woeful recent efforts.
"It's difficult for me to find explanations for poor performances like this week after week," he added.
"I make myself sound unbelievable if we then don't deliver on the pitch.
"We were missing everything that makes us Schalke. There was no passion, willingness to run or emotion.
"It's a mystery to me that we didn't stick to what we set out to do. Everyone has to ask themselves whether they really put everything into action. It's sad that we played that way."
