The Wanderers hadn't won a Barclays Under-21 Premier League match this season until the visit of Rovers to the Reebok on Monday night, but they ran out comfortable winners.
"I'm bitterly disappointed with the performance," said Kinder.
"We let ourselves down coming off the back of a decent performance against Stoke City in the previous game.
"We never got the tempo of out game going, our ball retention was poor, it was a very disappointing night."
The only bright spot was the return to action of injured duo Darragh Lenihan and John O'Sullivan. Lenihan had been sidelined since February with a back injury, whilst O'Sullivan damaged ankle ligaments in pre-season.
"The only positives were John O'Sullivan and Darragh Lenihan," added Kinder. "Just to get those two back playing was a massive plus.
"Darragh came through 45 minutes and John played an hour, both of those were planned and we are pleased that there has been no reaction.
"On the playing side I think only Dean Rittenberg gave us the only positive, I thought he was exceptional all night, his link up play and hold up play was superb.
"He was unlucky on two or three occasions, he hit the bar and had an effort cleared off the line. He is getting better in each game which is good, his first goal at this level can't be too far away.
"Overall we were well and truly second best which is unacceptable, we play Everton at Ewood next and there has to be a sharp improvement."
The Under-21s are next in action on Monday October 7th when Everton are the visitors to Ewood Park. Season ticket holders can see the game for free on production of their season ticket card. General admission prices are £4 Adults, £2 Concessions.