Plant Managers are the leaders of your organization. They should be someone who can really get a team behind them. They will be motivating, training, and disciplining their teams.
Today this could include managing the production schedules, plant safety, workforce staffing. Tomorrow the plant manager could be meeting with clients to give them status updates or pitching a new cell.
Plant managers are the oil in your engine, the jelly to your peanut butter. It just doesn't work without the other.