Boss Gary Bowyer pulled no punches as Rovers put in a below par performance as Brighton won 1-0 at Ewood Park.
Matt Kilgallon's first half own goal was enough to send the Seagulls back to the south coast with all three points as Rovers disappointed on home turf.
Jordan Rhodes saw a goal disallowed and a header tipped onto the post by Albion keeper David Stockdale, who also kept out a Markus Olsson strike.
But Rovers were rarely a threat, much to the disappointment of the Rovers boss, who was far from happy with his side's display.
"I thought the first 45 minutes was the worst since we've been in charge," Bowyer told Radio Rovers.
"The game wasn't a classic, you look at the standard of the goal that we conceded, it was shocking. The standard that we expect and the standard that we have set was not met today.
"In the second half I thought we had a bit more of a go, but you can't expect just to turn up and beat teams.
"I thought their goalkeeper has made two outstanding saves, Jordan's header that hits the post and Markus's strike from the edge of the box.
"I also didn't think there was an awful lot wrong with the one in the first half where the goalkeeper has fumbled it under a challenge from Jordan. I didn't see any contact.
"It looked like the effects from a tough period but there are no excuses from that. It is disappointing to finish the week in the manner that we have after coming into it after winning three out of three.
"It is a disappointing end and it is even more disappointing when it is in front of your home fans as well. I totally understand the fans frustration.
"We now go into the break with this result hanging over us, so it is going to hurt before we play Leeds."