Rookies from small colleges are usually just hoping to make an NFL roster, especially if they're undrafted. Becoming a starter in year one is certainly farfetched, and having one of the best seasons of player at your position is unheard of.
I have always thought that he was one of the most over looked Cowboys. From where he start he had a great impact as a rookie. I know for awhile he was the only player to lead the NFL in intercepts three different times.