I feel like a HOF player should consistently be a player that you would basically trade anyone for, or would love to have on your favorite team. I have a hard time putting Kurt Warner as a top 5 QB right now in the NFL let alone one of the historical greats.
If you look at it closely you will see that he has been good with StL and Arizona, both teams that play indoors in ideal climates. His numbers speak for themselves when he plays in bad weather (ex. Giants years).
My opinion, and I know it doesn't matter, is that he is a very good player, but not a Hall of Famer.
He has the 3rd best career passer rating of ALL TIME, has been to 3 SBs won 2 MVPs. What else does he need to do to be worthy of playing on your team?