BARNSLEY manager Gerhard Struber felt that some of his players failed to play at 100 per cent in the Reds 2-1 defeat to Derby County on Thursday night.
The Tykes trailed 1-0 at the interval through Jack Marriott's opener, assisted by Wayne Rooney, before Elliot Simoes dragged Barnsley level.
Martyn Waghorn scored the winning goal just before the hour and Struber feels that Rooney's influence was a key factor behind a first defeat in five games for the visitors.
Simoes was a 26th-minute substitute for Barnsley, with Michael Bahre making way after the Reds had endured a sluggish start.
Goalkeeper Sami Radlinger was in inspired form for the Tykes, pulling off a string of fine saves to always keep Barnsley in the game.
"We lost simple balls and the impact that Rooney had with his energy, we had a lot of problems in the first half, especially in the first 25 minutes," said Struber in his assessment of Barnsley's defeat.
"With the substitution we gave Derby a few more problems in the last line. Elliot was good for our offensive game but in the end it was not enough for a point.
"It is painful now. It is a disappointing situation but we need to work in the coming days."
Of Rooney's influence, Struber added: "I think with the energy from Wayne Rooney, all the players in his team wanted to show him what they can do.
"That was the plus for them today. That energy was big for Derby."
Struber has been impressed by Simoes on the training pitch, with the 20-year-old's 50th-minute strike marking his first goal at senior level.
The Reds had struggled to retain possession for large parts of the first half, with Simoes introduced to give the visitors more of a foothold going forward.
Struber said: "I think the first 25 minutes showed me that we needed more action between the lines. In training Elliot has shown me that he is a very good player and a big talent.
"And now he has created a very good performance and I think it was the right substitute to make.
"He is very quick. He also thinks quickly. I am happy with his performance but not every player was at 100 per cent.
"When we play a big opponent, who have someone like Rooney, with this energy, we need every player on their limit.
"And today there wasn't enough from every player. It wasn't what you need to win away from home."
Yesterday evening's match was Barnsley's fourth game in 13 days but Struber insisted that was no excuse for their slow start.
"The opponent also has many games, it is not only our problem," he added.
"It is not easy. We don't have a big squad to change players. This is our challenge, this is my challenge.
"So it is not always easy to have the right energy for these games."