How much training a player receives is based on a number of factors. 18 and 19 year-old players will train at an optimum speed and as the years go by, training will be harder. Also, players that get 48 minutes per week of training will get the most amount per week. Also, if a player has reached the maximum potential he can, he will train very slowly.
As far as your question goes...the stats visible by us (example: jumpshot is respectable) are only signs of what the real stats are. There are many sublevels of stats and so, while you may not see it, the player is still being trained.p Once the sub-level goes beyond a certain amount, you will be able to see a difference in his real level (ex: he will pop from respectable to strong).