Nottingham Forest captain Luke Chambers has questioned the team's work ethic after a dismal run of just one win in their last seven Championship games.
Forest are second from bottom in the table and have only picked up eight points from their 11 games this season.
Chambers told BBC Radio Nottingham: "Are we going the extra yard? That's the question we have to ask ourselves.
"Are we trying hard enough to stop the cross, to stop people getting free headers in the box?"
Although centre-half Chambers believes there were positives to take from the performance, he said their defensive efforts this season have simply not been good enough.
Last term, the spine of goalkeeper Lee Camp and centre-backs Chambers and Wes Morgan provided a solid platform in the club's run to the play-offs.
But they have conceded 22 goals in their 11 league games this season and Chambers said: "It seems to be a recurring theme at the minute that we are just not working as hard as we should be - as a team and as individuals.
"It's all well and good saying you've got to to play football, but first and foremost in this division you have to earn the right to play.
"I felt we did that in the first half [against Coventry] but in the second half, once our backs were against the wall, we didn't seem to fancy it.
"I thought we did really well first half and controlled the game. They had a spell for 10 minutes in the second half and we seem to have caused ourselves to lose the game.
"The cross hasn't been stopped and the ball hasn't been defended properly. It's the same old story."
The Reds have had a traumatic beginning to this season, with Steve McClaren resigning as manager and many among supporters angered by the lack of new signings.
Chambers was also worried by the lack of new faces arriving at the City Ground in the summer and feared it would hamper their hopes of challenging for promotion
But now Forest are more concerned by maintaining their Championship status than pushing for the play-offs.
"Until people start doing their jobs throughout the side we will not get out of this mess," Chambers added.
"People can say they are working hard enough but the facts are the facts. Crosses are not getting stopped and people are getting free headers - that shouldn't be happening.
"People have to stand up and be counted."