Like Viejo said, his Playoff numbers and clutch performances in the biggest games are only surpassed by the greatest, Jerry Rice.
Additionally you have to consider the position he played - slot receiver, a position that Billy B put on the map with Troy Brown, Wes Welker, and by far the best of them all, Edelman.
He was not a "wide receiver". Name me a better slot receiver in the history of the game.
Absolutely, Hall of Fame.
Welker's numbers are better in every category