Ferran Sibila thanked Barnsley fans for sticking by the team in their 1-0 loss to Bournemouth, while adding: "we weren't able to put the ball inside the goal which is really frustrating."
The promotion-chasing visitors netted in the 12th minute to inflict a fourth straight league defeat on the last-placed Reds who are winless in 11 Championship games and eight points from safety.
While a section of the fans chanted against the board throughout, many stayed behind to applaud the team off after one of their better displays in recent weeks.
"I am frustrated for the lads," said Sibila who led the team in the absence of Poya Asbaghi who made decisions from home while isolating with Covid-19.
"Bournemouth were the better team in the first half, but we still had three clear chances.
"In the second half, we were more aggressive, which was the plan from the start, and we had four or five chances but we weren't able to put the ball inside the goal which is really frustrating. Everybody did their job in a good way. The fans were with us as well, mostly in the second half and it was a good environment."
When asked if it was too late in the season to focus on performances rather than results, given the Reds' position in the table, Sibila said: "Correct."
Defender Jordan Williams added: "We gave it our all, you could see that by the fans' reaction at the end, they were clapping us off and it hasn't been like that recently.
"We were unlucky. We didn't get the rub of the green.
"We tried to go back to basics today and go long at every opportunity.
"We are all upset that we didn't get anything from the game but we all still believe."
Barnsley missed several chances, with Callum Styles especially guilty of not scoring from close range.
Sibila said: "That is football. Sometimes it happens. The worrying thing would be if we were not creating chances. We just have to keep the confidence in the players."
Brad Collins raced out of his box but did not get the ball for the opening goal.
Sibila said: "It was a difficult day with the wind. We could see a lot of players were having problems with decisions, like that one."
It was a good day for Barnsley's youth system as Matty Wolfe, 21, made his full debut while 18-year-old Aiden Marsh, from Monk Bretton, came off the bench to play for the first team for the first time. They have both been in the academy for at least five years.
Sibila said: "We had a lot of players out of the squad so it is an opportunity for young players. They are both players who have been in the academy a long time. They got the chance they deserved from their training. Wolfie has been doing well in training and he gave a good performance. It was good to bring Marshy on so players from the town can play."
Victor Adeboyejo and Claudio Gomes were out of the squad after sustaining knocks on Tuesday at Nottingham Forest. Sibila would not say whether they or any other injured or isolating players could return for Wednesday's game with Cardiff but hoped Asbaghi would be back.