The only skill in a player's skill set that you cannot train in any way is
Experience.
We know from the game manual, in the Game Engine part:
A player must decide whether the opportunity presented is good enough to take a shot… this of course changes as a function of amongst other things… the shot clock, the players experience, the score of the game, the history of the quality of shots the team has seen recently, the offense the team is running, and whether that rookie shooting guard of yours thinks he knows better than the coach does how good he is at making jump shots.
We also know from the manual that almost all games add experience to players, including scrimmages. The manual mentions specifically that B3 games and NT games add to the players' experience too, but nothing more is said about this allusive mysterious quality.
So we know it matters, the manual clearly says so. I personally saw older players with low skills sometimes take many offensive rebounds at the end of games.
We also know how to gain experience. Age is a huge factor, but also crucial games like B3 and NT (and somewhat U21 NT) play a big factor. After that it's playoffs, cup games, regular season games (do TV games add more?), and lastly scrimmages. Private leagues do not add to a player's experience, as it will help supporters over non-supporters.
But how much does it really matters, if we want to quanitfy it? I would obviously pick an experienced player over the same exact player who is a bit less experienced, but that's never the case.
Can I say it matter over free throws or stamina? Does it matter over main skills? I heard people say it matters more in the playoffs than in the regular season, is that true?
By the way, you can sometimes find very young players who are highly experienced. Players from small countries, for example, who played for their NT since they were 24. Also, every new team seems to get at least one very experienced player. You can find in the market low salary players that have more than 17 experience, even though they are only 25 and never played in the NT or the B3.
So, what are your thoughts on the matter? Do you even look at that skill when you buy a player? Will you take it into consideration when you look for a player? How much does this interesting skill matters, to you and to the game engine?