When you are purchasing an 18 years old trainee, how much attention do you pay to his stamina or free throw skill?
I disagree in part with the previous poster. Free throw I agree, you should pay zero attention to (as soon as your team is established, has a healthy economy, and you have invested in your arena to a point where you are meeting demand for tickets, you should then buy the training court to increase your FT levels across the board on your whole team).
Stamina is hugely important though, and is something I personally would consider a deal-breaker on someone with atrocious stamina. Pitiful is also no good, I would generally consider awful as a bare minimum. Of course, all things are relative, if it comes down to a binary choice between a 53 TSP player with inept stamina, and 60 TSP with pitiful, then the extra 7 TSP would in nearly all cases outweigh 2 stamina. But you then also have to consider the difficulty in getting this poor stamina player 48+ for full training, and the impact to performance both through the training years, and the later years when you need to train stamina for half a season once he's reached his final build.
As a rule and to avoid disappointment and frustration, awful is almost always my bare minimum, and mediocre is a desirable base line.