Barnsley's poor performance in a 2-0 loss at Preston North End was a 'normal human process' in their first game after their place in the Championship play-off was secured, says Valerien Ismael.
The Reds conceded either side of the break to set piece goals and lacked their usual intensity in their final away game of the season.
Ismael told the Chronicle: "We didn't give the performance we wanted and it is a big disappointment. It is a typical case when you reach your goal last week then the pressure comes down and you switch off for a short time. It is a warning to refocus, come back to our intensity and have a good week of preparation for the last game against Norwich (next Saturday).
"The goals showed it is a concentration problem, the guys switched off. That is a normal human process.
"It is the only explanation. The training week was good but, at 3pm on Saturday, it was like the guys switched off completely. My job is to refocus the guys now and get a much better performance against Norwich and find our identity again."
Defender Toby Sibbick added: "With us securing our place in the play-offs, it could have been a little bit of a lapse in concentration. "But that can't be an excuse, we need to get back to our best and have momentum going into the play-offs.
"We have scored our fair share this season from set pieces so, to concede two and lose from set pieces in a game which didn't have many chances, is disappointing. We have to get it out of our system and move forward to Norwich."
Ismael started Conor Chaplin ahead of Carlton Morris but reversed that at half-time – after Chaplin missed a fine chance – as he made three changes at the break.
Ismael said: "We wanted to get Chaps between the lines with his agility. He had a big chance in the first half. If he can stay calm and score, it could change the game. The performance was not enough and did not meet our expectation. At half-time, I could have changed six or seven players."