I was doing some research for a different fanpost that I haven't made yet, and took note of his stats.
The guy has 65 career interceptions. Only 4 players have more, and they are all in the Hall of Fame. He has more than: Ronnie Lott, Dick Lebeau, Emmitt Thomas, Mel Blount, Lem Barney, Darrell Green, Willie Brown, and Deion Sanders. All told, there are 27 Hall of Famers with fewer career interceptions than Riley.
Of all currently active players, the only one who has a realistic chance of passing him is Ed Reed, who currently has 61. Charles Woodson would have to get 10 before he retires to tie him, and Champ Bailey needs 13. Woodson has 10 over the last 3 years, and Bailey took 6 years to get 13. They are 36 and 34 respectively, so they probably aren't passing him.
He also returned 5 of those interceptions for touchdowns. Of the players above him on the all time interception list, only Rod Woodson has more. (Paul Krause only has 3, Emlen Tunnell has 4, and Night Train Lane tied him with 5). Of all the Hall of Famers, only Deion Sanders, Ken Houston, Lem Barney, and Herb Adderley have more interception return TDs.
He was never selected to a Pro Bowl, and wasn't selected to an All-Pro team until his final season. His teammate Lemar Parrish, however, was selected to the Pro Bowl 6 times as a Bengal, despite having a better season than Riley only once in his time on the team.
This was never more unfair than the 1976 season. Lemar Parrish was selected to the Pro Bowl that year, after only making 2 interceptions for 0 yards and 0 TDs. His other teammate Tommy Casanova was selected to the Pro Bowl that season as well, and was a 1st team All-Pro. Ken Riley picked off 2 more passes than both of them combined, and set the franchise record for picks in a season that stood for 29 years until Deltha O'Neal broke it in 2005. Yet his two teammates were picked for the Pro Bowl and he wasn't.
So, tell me, with the career this guy had, why is he NOT in the Hall of Fame? He had a better career than many defensive backs who have been in the Hall of Fame for years, and was the best DB on his team for pretty much his entire career.
Oh, did I mention he spent every year of his 15 year career as a Bengal?