What's he missing? Only thing I can think of is longer range passes. Maybe positional awareness if he's never played deeper. He's got the engine, close control, drives us up the pitch, wins the ball back well, good skill and passing in tight spaces.
I've always kind of agreed with this take. I think he would have potential as an 8, with the exception of his long-range passing as you said. I always thought that COH is low-key quite good defensively, at least in the sense that he wasn't afraid to track back and get stuck in, but I suppose that doesn't exactly translate to him being equally successful in a deeper position. But I seem to remember him being in and around the box defensively, getting involved, especially when we launched counter-attacks? Been so long since I've seen him play, I could be making things up now!
I think he's just too good an asset in the 10 role to really sacrifice his ability in order to test him in the 8 position. Though if we find ourselves in a situation where we have injuries and an overload of quality competing for the 10, like if Tats comes good and Palmer is firing, then who knows, maybe COH could be deployed there in a scenario where Hamer is sold last minute and we can't find a replacement. Wouldn't surprise me!