Funny you mention that Everson Walls gets no respect because unlike now, I was following the NFL heavily back then and I always considered him a star. He led the league in Ints several times and was first team All Pro several times as well. As a matter of fact, I still store his RCs in with the rest of the 1982 Topps stars.
The only reason I would have given him as the answer as to who was covering Dwight Clark on "The Catch" is because he was the first Dallas DB from that era that would come to mind. I actually did not know that factoid until you posted it.
One thing that illustrates the popularity of the Cowboys "back in the day" is how many non HOFers from that franchise that are quite famous. Don Meredith, Lee Roy Jordan, Walt Garrison, Tony Hill, Too Tall Jones, Harvey Martin and Everson Walls are some of the forner Cowboys that are more well known than many actual HOFers from other teams. Not to mention Jerry Tubbs!!!!