Walker was Karl Dorrell's #1 choice from day one. Walker is supposed to be very highly regard in the NFL, and that he was expected to take the next step to a DC.
The deal isn't entirely done, since Walker and UCLA are still in the process of discussing the defensive assistants Walker could bring with him. We've heard that a new defensive line coach could be likely.
Walker also is thought of as a very good recruiter -- on par with Eric Bieniemy, the running backs coach that just departed UCLA for the Minnesota Vikings. Former defensive coordinator Larry Kerr wasn't considered a great recruiter, so Walker is thought to be a tremendous upgrade.
Sources have also indicated that it's unlikely Ken Norton, the former Bruin and current USC linebackers coach, will come to UCLA.