He could well be a dud, but I'd go easy on relying on the opinions of previous coaches for the simple reason that none of them really based that verdict on a rather salient data point:
"Playing football for Swansea City."
As has been pointed out by others, letting 'training kings' and teacher's pets dictate the team leads to Jay Fulton being welded into the midfield for months on end. Myk may be shit, but we never got to find out one way or another in any sense that matters.
His attitude being awful is the only thing that makes sense to me. But I hope if that's true it was genuinely shocking and not just a case of him not being a teachers pet. A lot of great players would not have made this Swansea team if we only played the boy scouts.