I don't know why it happens, but fans of teams have a tendency of overhyping Player X just to make Player Y look worse than they are.
It kind of makes sense when comparing players from different teams, but I think the majority of the time it is done with two Players from the same team.
As far as Lewis. The guy can make plays. But also is not the biggest or quickest CB out there. If he was as athletic as Brown or as big as Byron, he would probably be that shutdown corner.
As of now though, IMO, he may never be a guy who can shutout everyone he faces every week, but he is capable of making defensive plays that not a lot of CBs can.
He's a guy every team can use even if he is never a superstar.