Overinflating Rookies?

[sethc13]

This is a general draft question:

How come so many 'draft experts' and fans seem to overinflate the value of rookies and undervalue former Day 1 picks that haven't had the opportunity to perform yet?

I've seen a number of examples of this in the last few weeks:

(1) Ashton Youboty (Bills): a number of pundits have stated that the Bills should draft a 1st Round CB since Youboty is an 'unproven' CB even though he was graded as a 1st Round CB but dropped to the 3rd.

(2) Marlin Jackson & Kelvin Hayden (Colts): with Jason David likely going to the Saints, people have repeatedly focused on the Colts need for a CB in the 1st Round. Do people forget that Jackson was drafted in the 1st and Hayden in the 2nd three years ago?

Shouldn't their experience make them better than a 1st Round pick this year? Why do people seem to think 1st Round rookies are immediate All-Pro players, yet after a few years of learning behind veterans lose their abilities?

I understanding wanting to draft at these positions for depth purposes, but 'draft experts' and fans too often forget about these players that have been learning these sytems and will almost certainly be better than a 1st year player. Forgetting about these players will lead 'draft experts' to make bad predictions in the draft (see Mel Kiper).

[Shzm13]

That's why you always gotta keep in mind that more "Can't miss" prospects miss more than often.

The combine really inflates them as well. For example, take a look at Greg Olson TE Miami...He was a 2nd rounder until he ran a fast 40 @ the combine. Watch the guy play in a game though, he is a very below average blocker..and will struggle at the next level where everyone is bigger, faster, stronger.