I'm not defending Mac Jones here, he sucks and much of it falls it his feet, but who wouldn't have been a bust with the OL and weapons the Pats trotted out the last two seasons?
A lot of QBs? I mean, Mac's only success in the league came as a rookie when they had an excellent O-line and spent a ton on weapons for him. Go look up articles after that year, everyone was talking about how great a job the Patriots were doing developing him and how the other teams (Jets, Jags, Bears etc.) didn't and how it was a blueprint for how a smart organization helps a young QB.
The playmakers aren't good.... they also look much better when they have better QBs, the All-22s show guys open that Mac never looks at, the route trees are limited by his faults, it's a poor room, it's not the reason he's bad. The line was only bad this year when obliterated by injury it was average in 2022, Mac was still terrible.
Mac didn't develop for the same reason he was the 5th QB taken in his class... he can't consistently drive the ball outside, he doesn't throw guys open, he makes poor decisions, his footwork sucks, and he's scared of even a moderate pass rush. Sure it imploded when the line got hurt, but plenty of other QBs have line injuries, it hurts their performance but it doesn't turn them into an unplayable mess.
Edit- the ability to play well when your line isn't great and you don't have guys wide open every play is what separates NFL QBs from OOGs.