Is Zinchenko really a mediocre player? He's a good player. He's just lacking physically, he's brittle and he doesn't have an ironclad focus and temperament.
He could've done a tolerable job at left 8 for us many a time. It's just Arteta's understandably always selected Xhaka or Rice ahead of him. And though it's slightly embarrassing for him he's been upgraded by a teenager, that's one of the best teenagers ever to do it, who's also keeping Calafiori out of the side rather often.
Zinchenko's on a CL wage but it's not high compared to our standard. For example Merino and Calafiori are both at a similar mark, and either could be where Zinny is in two seasons if persistently injured or squeezed out.
Tough to move him but it's because he's got the traits of a guy who should play in Italy or Spain, but a life in England on Arsenal wages. I don't see us engineering these problems all the way out of our squad management.