I regularly teach students about the classic screening models in Economics. For the uninitiated, this is when the abilities of individuals are assessed by an uninformed person before a trade is completed. I use all the classic examples; job interviews, credit rating checks and medicals for sport stars prior to transfer - these activities all attempt to screen out the lemons! Nobody wants to buy a dud and they realise the selling side may be privy to sensitive information they wish to keep secret.
This leads us to the recent transfer of Sandro Tonali from AC Milan to Newcastle. It struck me as odd that AC Milan would sell one of the best defensive midfielders in Europe at the age of 22. It has now come to light that the player was making bets on AC Milan matches during his time with the Serie A side and faces a 10 month ban from football. This could be up to a three-year suspension under FIFA rules if the player chooses not to cooperate.
Did AC Milan engage in opportunistic behaviour? It is plausible that the selling club knew about this behaviour and benefited. While Newcastle likely did a professional job screening for all the potential lower limb problems and underlying physical issues, perhaps their screening failed elsewhere.