Barnsley produced a spirited and impresive performance going forward and levelled twice through goals from interval substitute Conor Chaplin and Cauley Woodrow in the second half, only for a late strike from two-goal Bradley Dack to win the game for Rovers.
It took Barnsley's goals against tally for the season to 36, with plenty of evidence shown as to just why the Reds are propping up the Championship.
On his first game in charge, Struber said: "I think the performance was okay and we made it a good game.
"But unfortunately, we made mistakes and the mistakes broke our game plan.
"When I look at this game, I think we had good moments and very good situations on the ball. But off the ball, we must learn that over ninety minutes, we must have high concentration and focus.
"I think the mistakes were ones that we created. We hope we can get better and work hard with the boys to make it a better situation next time and we will win the next games.
"I think we created chances and good situations and we had control. But at the end, we did not cover the opponent and then we lose and then the situation is not so funny as we need the points and at the moment, I feel pain.
"In this game, I learned that we need focus and concentration for ninety minutes and in every second on the pitch. This is what we will do in the training and next games.
"We need a high focus on the personal task and when we do it, we have the best chances to win the next games.
On the impact of Chaplin from the bench, he added: "I think Conor made a big difference in the second half.
"He showed me what he can do and he is a very interesting player and I hope he plays in the same style in the next games.
Aapo Halme, who started in a holding midfield role came off at the interval, but Struber is hopeful he will be available for Wednesday's crunch trip to relegation rivals Middlesbrough.
"He had problems; a head injury. I hope it will get better and he can play on Wednesday," Struber said.