My only disagreement with your analysis is that you seem to assume that "strong core" is handed to you on a platter. If you are able to acquire such players, perhaps you are right but it takes a lot to get there. I've been playing this game for more than 10 years and very few of my teams have many players which have been with their respective teams more than 5 years. Trading and drafting are my two favorite aspects of PB so I tend to turn players over fairly rapidly.