Well, despite Jernigan's SB return(s) at end of his rookie year, he never had any kind of return game--unlike, say, Wilson, who DID succeed almost immediately in the return game throughout his rookie year.
All this fantasy about Coughlin and Gilbride deliberately, or incompetently, sabotaging Giants offense specifically by withholding Jernigan from the field FOR NO REASON--because after all that is what you and your cohorts are saying with your thinking on this subject-- is plain nuts.
And of course there is the other part of this equation that no one seems to consider. That it may well have taken this long for Eli to trust Jernigan enough to throw the ball his way in various situations. Every QB has one or two receivers he trusts in ALL situations more than he does other receivers. It's easy to sit at your computer and say in hindsight "see, I told you......!" after the fact, but nobody knows what is REALLY going on between QB-coach-receiver in practice or in an actual game. That's a ten-four to you, buddy.