I've heard the "left wide open" bs many a time when it comes to showing some of Kupp's TDs. There's no question that a lot of Black DBs stink at coverage, we see illustrations of it all the time, but when a receiver is open time and again in great deal it's because he knows what he's doing and he's very good at it.
On a different tangent, I just love how announcers give lavish praise when a Black receiver tries to come back to a QB who's under duress or otherwise changes his original route in response to how a play is unfolding. Every football player from the age of 6 should know that's what you do in that situation, but a helluva lot of "professional" receivers just run their route and that's it. Just another example of how the basics of the game have changed over the years in response to the Caste System. Of late I've been seeing more successful Hail Mary passes, because the defenders in the endzone were just milling around more than actually defending the incoming pass. There was a completed one during the LSU-Florida game last Saturday that was the weakest attempt by defenders I've ever seen.