The Ravens were beaten 24-18 by the Cleveland Browns yesterday, leaving themselves without a victory since week five of the season.
The reigning Super Bowl champions are currently third in the AFC North and face an uphill battle to reach the playoffs following their recent form.
"It's obviously frustrating. We just haven't been good enough. It's not easy on Sundays when you're going out there and it's tough sledding and you're not getting the job done," Flacco told The AP.
The Ravens will have a chance to close the gap on the top two in the AFC North on Sunday when they face the Cincinnati Bengals, who currently top the division.