Byram was at a bargain price and too good to ignore.
He is quite experienced and is English(which puts a premium on his value). He may turn into a good right back and become a good premiership player, for Everton in the future or a player that we should make a profit on if he didn't make the grade as a top player.
I think the manager was honest with him, and Byram realised that he had Coleman ahead of him , Browning, Pennington and Kenny coming on as well , it was going to be very difficult to really establish himself at Everton.
WHU offered greater opportunities for him and he took them.
I suppose it does throw a question mark about the future for some of our younger players who can play right back.