Nice game from Denver, though the Cards also handed it to them. Those early picks by Rosen just killed them, and being sacked 6 times didn't help.
Regarding Nate Peterman, I decided to look a little into him, doing my best to not bash the guy, just stick to the facts as much as I can. First, he's only 24, so who knows what will happen in the future, but right now, he looks like, at best, a career backup. He gained notice first at Tennessee, then in the Senior Bowl. He was one of 15 QBs at the Combine, and threw okay, with just okay numbers. The Bills took him in the 5th round. Last year he was named the starter in week 11 against the Chargers, and threw 5 interceptions, an NFL rookie record. He played again in week 14, in the snow, and was 5-10, for 57 yards. He played some in the playoff game against the Jags, and threw another pick. With those kinds of numbers, it was almost surprising they invited him back to camp.
Somehow, some way, Peterman really stepped up in camp, and during the preseason, where he had a passer rating of 124.7, which is just superb, 3TDs to only one pick and an 80% completion percentage, with the longest average throws in the league at over 10 yards per attempt. These are Drew Brees type numbers. After this, the Bills said he earned the right to be their starter over Allen, and McCarron, who they even traded away. But the preseason is really not the regular season. Coaches try some things, don't try others, are mostly evaluating, and often playing 2nd, 3rd, 4th string guys. For example, EJ Manuel also had a preseason passer rating of 120.9, but if you saw him play you realized he wasn't that good, and the Raiders cut him. Kyle Sloter had a passer rating of 114.1, Joshua Dobbs 112.0.
Fast forward to the regular season, and Peterman has gone back to 2017, playing in just over two games, his passer rating is 16.7. He's thrown 1 TD, and 4 INTs. His average throw has been 2.8 yards. His numbers are so bad, he's the worst QB in the league with over 30 pass attempts, out over 40 QBs with a QBR of 6.6. Granted, the Bills OL is a mess, and they don't have many playmakers. But even Josh Allen, who everyone knew would take time and needed to develop has been significantly better, and his numbers aren't good either. 61.8 passer rating (29.2 QBR), and this after they basically threw Allen to the wolves.
So, if the Bills signed Derek Anderson as their backup, why don't they just cut Peterman? My guess is because he's only making $550,000 this year, and having him on roster means they can choose a time if they want to release him when it's least likely he'd be picked up by someone else, and push him to the practice squad, and maybe, since again he's only 24, he'll somehow learn and be a competent backup in the future.