The Hoops suffered their second domestic defeat of the season when they crashed 1-0 at Rugby Park courtesy of a Youssouf Mulumbu goal.
Celtic were hampered by injuries to Dedryck Boyata and Kristoffer Ajer but Rodgers says that was not to blame.
“We could’ve played here until midnight and not scored. We weren’t really threatening,” he told reporters.
“We were disappointing. Defensively, we were a bit passive at times, even though we didn’t have so much defending to do.
“We can blame injuries, we can look at the pitch and all sorts where it’s very difficult to play, but the bottom line is we weren’t so good.
“Very disappointing result.”
Uwe Rosler was sacked by Fleetwood following a 3-0 reverse at Doncaster which condemned Town to a seventh straight defeat in all competitions.
Cambridge interim head coach Joe Dunne was pleased with how his side adapted to beat Grimsby 3-1.
Southend manager Chris Powell led the applause for Jason Demetriou after the right-back scored twice in the 3-1 win against Portsmouth at Roots Hall.
Morecambe boss Jim Bentley was the happier manager after Gregg Wylde's 90th-minute strike earned his side a point in their 1-1 draw with Forest Green.
Manager Gareth Ainsworth described Wycombe's 2-0 win at Cheltenham as a thoroughly professional performance.
Skipper Richard Wood scored the winner just before half time as in-form Rotherham pulled off a 1-0 victory at League One leaders Shrewsbury.