"Toughness" has some overly masculine connotations.
I prefer to think of it in terms of focus and concentration.
And part of that, perhaps the most important part is the ability to ignore distractions and irrelevancies.
In a sport such as basketball, physical attributes will always play a part. Those can be built upon by improving strength, fitness, etc.
Then you have what is loosely termed "natural ability" which can be regarded as how good somebody is without practice. And naturally those skills can be improved with practice.
What many people don't understand is just how import focus & concentration is when training.
As a simple example: If you stand randomly at the line, casually throwing balls at the hoop, whilst chatting or thinking about your girlfriend, etc, it doesn't matter how much you practice you will simply teach yourself to be a mediocre FF shooter.
Then of course you have knowledge & intellect. BBall isn't just a shooting contest. At the elite level, many would argue that running the plays, and defending, is just as important as ability. So again focus and concentration comes into learning and executing those plays.
What you might call "execution" is pulling it all together in the game. And there, Focus is everything.
I would argue that the difference between very good players & teams, that win a lot of games,
and GREAT players & teams, that win close games and championships, is their ability to focus and continue executing under extreme pressure.
I'll give you two examples:
Go back and what some of the classic Jordan games. He was a talented player anyway, but his ability to stay focussed no matter the score, or the preceding play, is what won him those rings. As a classic example have a watch of the "Flu Game." (Probably actually food poisoning.) He was literally physically too weak to be on court, yet led his team to victory through sheer willpower.
The other example is Rotnei Clarke. As an average 6ft white kid, he basically has no business being a professional baller. Yet he has worked his arse off to develop above average skills, and become a truly elite shooter.
The legend says that as a kid he would shoot 500 baskets a night. That might be an embellishment but I think indicates his focus and dedication.