In 2019, the Bills were 25th in passing yards, 31st in completion percentage and 19th in yards per pass. Yes, I know that Matt Barkley played two of those games, but his numbers in these stats weren't much different than Allen's. I just used team stats because individual QB rankings drives Allen down since there are other QBs higher than him that played a half a season or less.
But as for individual stats, Allen had a very mediocre 58.8% completion percentage, 6.7 yards per pass, and 193.1 YPG. His QB rating was 85.3. Just to compare, last year he completed 63.3% completion rating, 6.8 YPP, and 259.2 YPG with a QB rating 92.2 QB rating.
And unlike a lot of other people, I think Allen's year last year was overrated. He was inconsistent. That is why from mid-October to mid-December the Bills went 3-5. When he was on, he is as good as or better than any other QB in the league. But he had more than a few awful and/or subpar games like his three INT, no TD game vs. the Falcons or his two INT and no TD game vs the Jags.