The answer

For anyone that was curious, the answer to the Zack Duke question yesterday (how is he not on the 40 man roster since this is his 4th year with the organization) was found at Baseball America by a friend of mine from Boston (if you can call Red Sox fans friends):

Players who were 18 or younger on June 5 preceding the signing of their first contract must be protected after four minor league seasons. Players 19 and older must be protected after three seasons.

Duke was drafted out of high school, and thus must've been 18 at the time. Thanks Jon.