Patriots talent pool drained
Jim Davis / Globe File
Bill O'Brien (center) is not the first assistant coach to leave Patriots head coach Bill Belichick (left) out in the cold. In Belichick's 11 years in New England, many of his former assistants have left the organization for greener -- and sometimes not-so-greener -- pastures.
Here's a look at some important former Patriots coaching personnel and where they are today.