But MLB is one position where rooks have stepped in, started immediately and made a big impact. Urlacher, Lewis, Vilma, Z. Thomas, Lofa Tatupu are all examples of MLBs that made huge impacts on their teams as rooks. The success rate may be close to RB in terms of immediate impact.
If Willis is the pick, I suspect he will be a huge upgrade in run D from Fltecher, but a downgrade in pass D, at least at first. With Simpson and Whitner have a year of experience in the system, I think Willis will be used closer to the line of scrimmage than Fletcher last year.