Danny Wilson locked his Sheffield United side in the dressing room for almost an hour and a half after the 2-0 loss to Crawley.
Errors by centre-half pairing Neill Collins and Harry Maguire let the Reds in twice in the last 13 minutes as Billy Clarke and Paul Hayes secured victory in Tuesday's League One clash at Bramall Lane.
The Blades hit the woodwork through Ryan Flynn's angled drive in the first half and captain Michael Doyle's dipping volley three minutes into the second period but failed to score for the fourth successive home game.
Wilson said: "There's been a great chat about it, and I think that's what it's been. I don't think it's been a cup-throwing type of conversation because I think we're beyond that at this moment in time.
"We've been done by a couple of mistakes from two boys in particular who have been outstanding for us the last couple of seasons.
"Unfortunately it cost us in the game but we've had enough chances as well, we've had good chances, hitting the post - we're quite unlucky in that respect.
"Not putting the ball in the back of net has been our problem recently, as you all know.
"If there's anything to look back on on the night, it's that we've had a couple of results that have gone for us as well. So all it does is knock us down by a game."