Damien Johnson felt his side put in a below-par performance against Aston Villa despite the Under-21s reaching the end of season promotion play-offs.
After going behind early at Leigh Sports Village, goals from Anton Forrester and Joe Rankin-Costello saw Rovers lead at the break.
However in a dramatic end to the match Andre Green grabbed an equaliser two minutes from time, but the point was enough to see Rovers finish fifth.
"I think overall we were disappointing," Johnson told Rovers PlayerHD.
"Obviously we drew the game but in terms of our performance we were nowhere near the levels that the lads have set themselves and what we expect from them. So from that point of view it was disappointing.
"In recent weeks we had set good standards, we've been good off the ball with our shape, we've been disciplined and our work-rate has been good and teams have found it difficult to play against us. And I think over the past few weeks we've got better on the ball.
"But tonight I think we were poor in both areas, they caused us a lot of problems and we didn't cope that well."
The result means Rovers will now play Arsenal away in a one-legged semi-final after the Gunners missed out on automatic promotion after going down 2-1 at home to West Bromwich Albion.
"It is another game for us and it is good for the lads' development to play more games," added Johnson.
"But the key thing is the performance. The performance of the individual and the performance of the team.
"To finish fifth is a good achievement, so credit to them for that, but the challenge is there for them to keep on improving.
"It isn't just about getting in the play-offs, they know that they have to keep improving, it is about them making the next step in their careers."
The date for the semi-final against Arsenal will be confirmed in due course.