The quarterback threw five interceptions as the Super Bowl champions were beaten 23-20 by the AFC East side.
The 28-year-old told reporters: "Things were going our way a lot, just not when I threw it to [the Bills]. We probably threw the ball for 200-something yards in the second half.
"So it's obviously not hard to get the passing game going. If I don't throw picks, then the passing game probably would have thrown for 300-some and we would have scored a couple touchdowns and maybe won the game.
"We're definitely going to get better, and we have to get better. A lot of that falls on me today just throwing the ball to the wrong team."
Flacco has thrown seven interceptions, been sacked five times and fumbled twice so far this season in the NFL.