As I'm about to show in my look at how a player develops, regular training development uses 5 points of the player's potential development points (Potential Ability - Current Ability).  I've now found proof that the occasional boost that coaching staff give players they work closely with happens outside of the normal training development and does not use up any of the player's potential development points. It's effectively a free/bonus upgrade for the player. Here is an example.  Chris