Stevenage manager Teddy Sheringham has questioned some of his players' commitment following their Johnstone's Paint Trophy exit at home to Dagenham.
League Two Boro have lost their last five matches in all competitions.
"I'm downbeat but you can't expect me to be laughing and joking, it hurts. I don't like losing," Sheringham told BBC Three Counties Radio.
"I'm not sure it's the same with everybody in that dressing room. I need to work that out."
Stevenage lost 2-1 in the second round to Wayne Burnett's Dagenham thanks to second-half goals from Jamie Cureton and Ashley Chambers, with Ben Kennedy's penalty providing consolation for Boro.
Sheringham's side, 20th in the table, have won just twice all season, and he says his side need to improve across the board.
"It's getting a bit of a habit coming out and saying that we're not quite good enough," said the former England striker.
"We are struggling as a team - we played some nice stuff but we need to play better all over the pitch. It's tough going at the moment.
"We said at half-time 'Do you know how many goals you'd let in during the second half?' And there was a deathly silence - at that point it was 16 or 17. That's a couple more for us to add up to the tally."