How transaction costs increase player movement under free agency. The Coase theorem does not apply when transaction costs are high; anyone know how much Scott Boras took home last year?
The doctrine of comparative advantage: the Rays and A's should trade for mutual benefit. Somewhere, David Ricardo is smiling. For background, take the example of Robinson Crusoe after Friday.
Our language is pervaded with causal accounts. To say something is "linked" to something else nearly begs the cause question. Gelman's account of effects of causes vs. causes of effects is recommended.
Baseball-reference's Play Index gets arithmetic operators. Note also the current free trial. If you don't feel comfortable with SQL, this easy-to-use service is highly recommended.