Richie Barker questioned his team’s attitude after they were thrashed 5-1 by League Two high-fliers Scunthorpe.
Michael Drennan’s late debut goal was the only bright spot on a day of misery for the Blues.
Iron midfielder David Syers fired a hat-trick as strike duo Sam Winnall and Paddy Madden extended the second-placed hosts’ unbeaten run to 16 matches in a one-sided game at Glanford Park.
The result leaves the Blues in 21st place in the table, seven points above the relegation zone.
Barker said: ‘I know what I saw and I will watch it again and we’ll go through it again.
‘One or two people need to have a good look at themselves.
‘To do that (deliver performances) week in, week out, you have got to have something about you.
‘And there are not enough players at this football club who do it week in, week out.
‘The statistics say that for three years we haven’t won a back-to-back away games.
‘And I don’t think we’ve won a back-to-back game all season.
‘That speaks volumes to me that we havent got enough players who do the right things.
‘It’s a very disappointing day for the club.’