I think you're right about that. And I think both he and Howley were probably hurt by having two high-profile teammates at the same position (Too Tall and Lee Roy Jordan). Even Harris maybe has been hurt by being linked with Waters. And Pearson looks, statistically, a lot like Tony Hill. They both look, statistically, a lot like Swann and Stallworth.
But I also feel -- especially at that time -- there was a bias against the Cowboys. I guessed it was because they were in the East with the Giants, Commanders and Eagles. A lot of prominent sportswriters probably grew up disliking Dallas. There also might have still been some ill will against the city a few years after the Kennedy assassination. Younger people can't know how much of a stigma that was for 10-15 years.
In any event, for a long time, the only Cowboys who got in were the absolute slam-dunk players (Lilly, Staubach, Dorsett -- those types). Howley, Martin, Harris, Pearson, Niland, Too Tall... guys like that got left behind. At least 1-2 should have made it. One could argue a case for any of them. Harris and Niland were hurt by the perception, at the time, that safety and guard were lesser positions. The truth is Too Tall probably affected games, consistently, more than Martin. He played the strong side and was devastating against the run, when running was still a very, very big deal. Too Tall also batted down who knows how many passes.