Mayfield's best plays are when he's able to roll out & make throws. Teams figured this out and try to contain him in the pocket. He's too short, and actually slow. Definitely has an NFL arm, but the throwing lanes are harder on the short QBs.
The other thing that's an intangible is Mayfield's attitude. It's no secret he went away from the team doctors in Cleveland & found one to clear him to play through that shoulder injury. Ultimately, it damaged his career in Cleveland, as he lost the locker room. He could have been even more of a king in Cleveland than LeBron.