This is fair and I had similar concerns until I looked into it.
2009, 2010 seasons the Browns improved their total points per game each season (though admittedly, only by a point or so each season). His QBs were Brady Quinn and Colt McCoy.
2011 - Miami went from 31st in the league in points per game to 20th in his lone season. His QB was Matt Moore who had the best season of his career by a long shot.
2012 - Put up basically the same point totals as the prior year though their defense was way worse than in 2011. QBs were Matt Cassel and Brady Quinn. Jamaal Charles had arguably the best season of his career. Of his OC tenure, this is the worst one.
Then with the Bills, they weren't very good years 1 and 2 but they had basically nothing at WR, and the ageless Frank Gore was their featured back. Once they upgraded at wide receiver and grabbed Singleton in the 3rd round, that was when they took off. Their #1 receiver in 2018 (John Brown) was their #4 WR in 2020. #2 in scoring points last year and #3 this year.