Hes very good with the ball, but he is passive with things like taking on the opposition full back or overlapping his winger on a consistent basis.
He has all the tools to improve his attacking output even within this team, AWB does it on the other side and is far less talented than Shaw which shows it is not just about the team he is playing in, but also about him
I agree technically he is a very good player, but again whether it is due to injury, playing in a poor team etc etc, he has not shown consistent enough performance over multiple seasons to be called best LB in the world