Terrell Davis is a hall of famer. A two time MVP, three time Pro-Bowler, 2,000 yard rusher, and two time Super Bowl Champion. All of that in 4 good seasons. Gale Sayers had only two thousand yard seasons(TD had 4 in his first 4 seasons), much less a two thousand yard season. He only played for 5 good years. He isn't in the top 50 in any major statistical category, TD is in the top 40 in Rushes, Rusing Yards, and top 30 in Rushing TDs.
Beyond the numbers, he was the backbone of an amazing team, lead by John Elway. It would be an error in judgement to not include Terrell Davis in the Hall of Fame. Not on the first ballot he is on, perhaps not for a decade. His numbers, ability, and the fact that he performed at a superior level for his first four seasons makes me think that he'll be there.
Cognito ergo sum.