Aberdeen captain Anthony Stewart admitted his side needed to play with more heart after looking like a beaten team when going behind against Darvel.
Stewart branded their 1-0 defeat against a team in the sixth tier of Scottish football a “disaster”.
The Scottish Cup defeat came on the back of a 5-0 loss against Hearts at Tynecastle and continued a poor run of away form.
The centre-back said: “As players we have got to look ourselves in the face and take full responsibility for that.
“The gaffer prepared us in the right way and we have let the gaffer down, ourselves down, the fans down and the club down.
“It’s the mentality from ourselves. We have got to look at ourselves and demand much more from each other.
“We have got to play with heart, we have got to play like it means a lot to us. We are going out there and coasting games and thinking that results are going to turn for us.
“We have got to work hard for things. We are not taking our opportunities and we are letting ourselves down.”
The former Wycombe player apologised to fans and added: “We prepared in the right way but we didn’t give it our all. Our mentality in the game looked like we were defeated.
“When we went a goal down, we looked like we were defeated.
“We have got to stand up and fight. Not a lot of us can say we did that, including myself.
“We have got top keep pushing and work even harder on the training ground. We have got to push each other and pull through tough times.”
The shock cup exit continued a difficult time for the 30-year-old, who was sent off in a league defeat against St Mirren and a Viaplay Cup semi-final loss to Rangers over the past month.
“I’m not shying away from what I have done in the past,” he said. “I take responsibility for my own actions.
“I am someone with a strong character. I will keep going, I will keep working hard.
“We have good characters and strong characters in there. We have got to go on the pitch and do it.”
Manager Jim Goodwin will bear the brunt of the criticism and his future looks in severe jeopardy ahead of Saturday’s cinch Premiership encounter with Hibernian at Easter Road.
“I feel a lot for the gaffer,” Stewart said. “He has given his all, he has given us everything we could have asked for and as players we have got to take full responsibility.
“We can’t keep coming out here feeling sorry for ourselves. We have got to roll our sleeves up and go again.”