If you looked at just numbers in a vacuum -- you'd have to wonder why She'll isn't in the Hall. But the reality is that he wasn't a Hall of Fame player.
Shell had a lot of INTs I his career -- but his prime years were late 70s and early 80s -- just look at the INT totals by QBs at the time. The rules changes led to more passing, but QBs in general -- including NFL MVPs like Bradshaw, Fouts & Sipe threw loads of them. It wasn't like Shell was dominant - his numbers benefitted from his era. He was good, make no mistake -- and hit was a great tackler, hitting HARD.
For my Money -- Troy Polamalu was leagues better, and Carnell Lake was better as well. Forget the stats, Shell wasn't a game changer on defense like Troy or Carnell (who played CB in 1995 replacing Woodson and helping turn an almost lost season into a Super Bowl run).
Greenwood is as much a HOF as the Packers Jerry Kramer and it's nonsense neither is in -- just plain jealousy by other voters. After that, the 70s Steelers have their fill. The reality is the Greg Lloyd &James Harrison and maybe even Joey Porter have a greater claim to be in the Hall but none likely ever will either.
Steelers who have legit chane at Hall now:
Polamalu - lock
Faneca - lock
Roethlisberger - lock
Cowher - 50% at best
Ward - will get in around 11th year or so eligibility
Greenwood - veterans committee choice only
That's it -- no one else really is in conversation .... YET.
Harrison gets in. He has the stats, infamy and highlight plays to woo the voters. I think you are going to see at least one more of the 2000-2010 steelers get in. It will be between Hampton, Smith, and Farrior, all who had far better reps and respect throughout the league than in the national media or in our fanbase. Hampton was the best 3-4 NT of his era. Smith the Best 3-4 DE, and the only reason Farrior is not spoken of in HOF terms is he played concurrently with Ray Lewis, who nabbed those all pros up. The NFL voters robbed him of a DMVP at least once. All three of these will likely be looked at better as the years go on and people realize exactly how great that D in that era was. You also have to look at Joey Porter, who has stats, will have some backing from Miami, and has several NFL record games from his all around play. he also has a very charismatic personality and looks to be staying around the league, meaning he will still have some contact with some voters and players to push his case.
I really doubt one lone player from it gets in and honestly I don't think it will be just two.. that was a magnificent 8 year stretch with a few other great seasons thrown in.
Shell and Greenwood have a long term shot with the Vet Committee, like Butler did. The four aforementioned in this post may have to wait till actual players are making the decisions as well. all of them may be still waiting decades for a final answer. on the plus side, all of these players will benefit from the use of advanced stats to paint a picture of how great they really were. its possible that as the next generation of media voters get in over the next decade, we see a greater move from the antisteeler bias the last two generations had and a greater reliance on something other than sacks, ints, and pro bowls
* there are two other guys that may get in long term... one will be Carnell lake, who's play style was every bit as dynamic as Woodson from the Cowboys, yet he gets most of the credit for the SS positions evolution in the early 90's from the press. the other would be Lloyd, who had no chance with the media because he literally treated them like crap. there was a two to three year window that he was nationally thought of as the best linebacker in the league, even gracing the covers of some national mags, which may be enough once attitude is out of the equation.
Its just a shame that Woodley decided to virtually quit after signing the big contract... had his numbers kept up he would have been a lock