Is he meant to be someone like Kelly? In which case he doesn't break up play enough. Is he meant to be a creative, passing player, in which case he can be too ponderous on the ball. Some people just haven't been able to pin down exactly what he's meant to do.
The last point is right, our fans don't understand his type of player so unfairly criticise.
Do Man City fans criticise Ilkay Gundogan because he's not as defensive minded as Fernandinho or as creative as KDB?
No, because they're intelligent enough to realise he's a different type of player.
Sheaf is a deep lying playmaker. Capable of breaking up play & is very effective at it but can also take the ball from the keeper & CBs & accurately progress it wide to the wing-backs or into O'Hare & the strikers which, again he's very effective at.
There's also a lot of misconceptions & confirmation bias based on a few errors which are latched onto but totally ignored when Hamer etc. do similar (and frequently far worse).
Sheaf actually breaks up play far more than Kelly & his Passing Accuracy is the best in the squad, both short & long. The idea that he frequently gives it away is utter myth.
He's literally just turned 23, younger than the likes of Shipley & still developing. His signing is a coup for us.