On one of my first trips to the Hall of Fame, I was able to interview a few players who were, themselves, Hall of Fame inductees. As was my habit then I'd ask them who they thought was missing from Canton and some of the answers were interesting, excellent players who were not on my list as "missing".
When I asked Dan Fouts he blurted out "Ed White". He and White were teammates and good friends but after several years of research that White was one of those whose career was better than his traditional "honors" (All-Pros, Pro Bowls, etc.) suggested.
Years later Ron Yary told me that yes, Ed White was indeed a great lineman, again a teammate, but Yary was honest in his evaluations. Yary also mentioned George Kunz as being every but as good as he, Dierdorf, Rayfield Wright, or Art Shell.
Bob Lilly told me "Roman Gabriel, his numbers are as good as anyone in here". That made some sense because for years Gabriel gave Dallas fits, when he was with the Rams and with the Eagles, even upsetting Dallas a couple of times in 1973 and 1974 and usually doing very well, sometimes whipping the Cowboys when he was with the Rams.
Hall of Fame guard Joe DeLamielleure has always maintained Bob Keuchenberg was the "prototype" guard of his era and he, John Hannah, and others used Keuch as the template for how to play guard in the NFL. Additionally, Joe D. thought Dave Butz was a Hall of Famer in terms of how difficult the big man was to move. He's mentioned others as well, like Joe Jacoby and Randy Gradishar as well. DeLamielleure is also high on Joe Klecko as well (Joe D. is a "big Hall" guy).
Another Hall of Famer, Art Shell, puts Gradishar in his top five "not in the Hall of Fame" along with his fellow Raiders Ken Stabler, Cliff Branch, and Tom Flores and Roger Brown, the Lions and Rams defensive tackle who attended the same college as Shell. Shell's word is highly respected among voters, I am told.
Merlin Olsen is also one who endorsed Randy Gradishar calling him one of the best linebackers he'd ever seen when playing or covering the NFL.
Rams defensive end Jack Youngblood thinks that Nolan Cromwell and Larry Brooks are two rare players who were dominant who don't get any ink whatsoever and thinks both are HOF-level players. He also says that Russ Washington, the Chargers right tackle gave him more problems than anyone, even Rayfield Wright, Dierdrof, and Yary. He also agrees with Yary that Kunz is in the same class with all of them.
Who knows what the future brings, but it is interesting the names you hear when you ask great players who they think are Hall of Famers because it does not always match with the media narrative.