With the Bills it all depends upon how their QB has or hasn't improved. IMO accuracy is not something that can be radically improved. You can tweak mechanics but it's about being able to throw with touch and anticipation. Allen came in with a cannon arm but how many QB's like that have we seen? Newton, and Vick both had accuracy issues with their cannon arms. How far you can throw it means nothing if you can't hit a receiver in stride. Throwing in practice isn't the same as throwing in a game. Josh has to prove he can consistently throw dimes before I'd say he's a good QB. Rothlisberger came in with a strong arm but he also came in with proven accuracy. That is why he's an elite talent. Rivers didn't come in with a strong arm compared to others but he had exceptional accuracy and the strength came later. Drew Brees also came in with what most though was marginal arm strength but again he had exceptional accuracy. Like Rivers, his arm strength improved with better training.
McVay prizes accuracy over arm strength because he knows the later can be improved with training. Accuracy has a lot to do with not only mechanics but a high degree of eye/hand coordination and beyond improving mechanics there isn't more you can do. Josh has to prove his inaccuracy issues are more mechanics than anything else. So far he hasn't done that. IMO this is the year he must show it. Allen's completion percentage has been subpar in his first two years. He must break 60% this year or the Bills need to rethink their investment in him.