He's poor and has been for the vast majority of the season . I do see some potential with him, there were moments yesterday when he had some good link up play with Asm and he put in a couple of good balls . There's also several times a game when he'll look for a pass either infield or forwards and there's simply nothing on. Defensively at times he's been shocking but that's not uncommon under Bruce as both flanks are criminally exposed. Though looking at goals conceded in recent games far more have come from moves the right side of the pitch than the left.
The requirements of full backs generally have changed, they're predominately a creative player now, they hardly ever seem to stop a cross or a man. Physically Lewis needs to be stronger but that should have been addressed the moment he joined, it's sadly too late for that for this season. Also his confidence looks shot and he looks to me like a player who needs to simplify his game.