Talk about the potential of a player is cheap because a player’s potential is the best that can ever happen in principle. Yet, everything that you can think of, including the very best, has a probability of happening. Unfortunately, for most players the chance of reaching the very best is very small. So all talk about the potential of the player without stating how probable it is that that player will realize his potential within X number of years, is pointless.
Talk about potential is extra pointless, because there is a very good alternative. Rather than talk about the potential of a player, it is much better to talk about the progression the player has made so far and then extrapolate that progression into a realistic story about the future development and growth of the player. Ideally, one explains what the player has achieved so far and then create a prediction of what teams he will play in the future and how well he will do in those teams. That way you can keep track of whether your predictions are anywhere near correct or not.
As an aside: even though talk about the potential of a player is cheap, that doesn’t mean that all talk about the player’s potential is correct. If you describe something about the player that is principally impossible for the player to achieve, then it ain’t a potential of a player. For something to be player’s potential he has to be actually able to live up to his potential. The reason I add this obvious note, is that I have seen at least one data provider that puts a number to the potentiality of every player, but that number is a value that mathematically a player can never ever achieve. So even though the value is presented as the potential of the player, in fact it is an impossibility.