Keep your ***-man and have him sort out all your potentials, then sort by "Job: Assistant Manager", then tag the attributes "Current Ability and Potential Ability rating/judging/whatever its called", then go at it. Its hard to recommend a specific ***-man as some people like theirs with 18+ motivational skills (easier for them to help you with team-talks), tactical knowledge (vital if your lazy in applying them and want the ***-man to do it), or like you, ability to accurately define what their current/potential ability is.