They all get an incomplete grade from me in terms of just how good they'll be. I think Allen is progressing as is Jackson. They have the benefit of more table coaching regimes around them, and they each have decent O lines in front of them with some decent receivers. Mayfield and Darnold should be OK. Mayfield will suffer from having a completely inexperienced HC and a very suspect O line, plus a man child at WR who despite being very talented would rather draw attention to himself wearing $100,000 watches to play football. Darnold's O line is suspect, he just lost a key WR, and his HC is a basket case. And you just have to feel sorry for Rosen.
I think Allen, Jackson, Darnold, and Mayfield will have long careers, maybe not elite but long. I think Rosen may say the hell with football after this season.