Barry Bannan gave an honest post-match assessment following a day to forget at Brentford on Saturday.
The Owls were well beaten 5-0 in the capital to extend the poor run of form in the Championship.
The midfielder said: “Not good enough, obviously.
“We’ve let the club down, let the fans down, let the badge down.
“There’s not much else I can say really, it was terrible.
“I’ve said it before and I’ll say it again, us as players have to start taking the blame now. The manager works hard, day in, day out.
“It might always come from me, it might sound boring but it’s us on the pitch now.
“You can’t go from playing as well as we did the other night against Manchester City, to coming here today and losing 5-0. It’s not acceptable.”
Bannan continued: “Nobody in that changing room can look themselves in the mirror tonight, we didn’t show up today and that’s what will happen in this league if you don’t.
“The gaffer has been more than fair with people, he’s given everyone a chance. Everyone in the changing room can hold their hands up and say they’ve had a chance.
“Our job as players is to go out and win games for this club and we’re not doing it at the minute.”