If I would see any purpose in striving for this level of separation I would use the DataMapper pattern (http://martinfowler.com/eaaCatalog/dataMapper.html), but I do not see it, so the Player etc. models would probably be ActiveRecords.
I've written lots of web apps using the plain ActiveRecord approach, and I've found it scales well to a given level of complexity, and then becomes hard to manage - hence trying something different.
