Really, his physical tools are average at best: below average height, average speed (unless he was faster than he looks on the video. But he had amazing hands, incredible instincts and body control, great route running, and very smart with his runs after catch.
If he were 5 inches taller and a bit faster, honestly could have been one of the greatest receivers of all time. Probably a ridiculous/blue-goggled assessment, but I'm seriously blown away after watching that video.