Keyshawn Johnson is not close to being a HOF and I would be very surprised if he is going to be a HOF someday .... Gruden put Johnson out the door in the middle of the season in 2003 when he had enough!
I admit I do not know much about Michael Irvin's situation but I think his problem was outside of the locker room ... Troy Aikman has said in the past that Irvin was a very good teammate ... Randy Moss, when he was with a HC that was respected (Dennis Green and Bill Belichick) and that the locker room had good leadership, Moss was fine ... That's when his HC was incompetant (Mike Tice, Brad Childress or the two HCs who had in Oakland) that Moss was a problem.
For Brown, it was a big mistake to give Brown too much freedom ... You can not do that ... You can not allow a player to think bigger than the team, otherwise it will always end badly. ..This player must always be disciplined, no matter what ... It's in hindsight, but Tomlin had made a big mistake when he gave only a $ 10,000 fine to Brown after the live facebook ... Especially there were rumors in the media that Brown was running the wrong road intentionally during the season (I think it was in the game against Miami in the regular season and maybe some other game) and you can not accept that!
But I have hope that Tomlin will learn from his mistakes