I said running back and linebackers as I coached several Heisman trophy winners and All-Americans at these positions in my NCAA 2007 dynasty. For running backs, the key is to recruit speed. Generally you can expect athletes that run 4.16-4.22 40s to fall into the 97-99 speed category. From there, just get them out in space. For linebackers, the key is good athletes that are big and fast then coach them up to blitz like crazy. I'd attribute about a quarter of my success to recruiting, a quarter to development, a quarter to in game coaching, and a quarter to creating the process and maintaining staff continuity.