Reminded me of Coleman when he first broke into the side. Potential in him I thought.
I can see where you're coming from.
However I think he always looked a bit out of position (which he probably was; I'm sure he was a CB).
He got beyond that through the general adrenaline of just breaking through into the 1st team; but that was never going to last.
CBs look great at full back when things go well as they're much bigger, generally, than actual full backs so when they're bombing on they look almost unstoppable due to their size and power.
Once form drops off, or the opposition catch on their weaknesses are exposed and they look lumbering.
I'd imagine that with a few injuries he's lost the momentum of his earlier appearances and he's falling between two stools - he's not good enough technically to be a full back and he's not good enough defensively to play CB.
If he's going to be a CB long term he's still quite young so he wouldn't be written off completely but they have stocked up on CBs.