When you're in the middle of your season, most of your free time will be spent practicing plays, scrimmaging and playing actual games. There isn't enough time to work on improving certain skills, and because you need to stay loose and flexible--and because you may be nursing injuries between games--you usually can't hit the weights enough to build more muscle mass. But those things can happen in the off-season, meaning year-round basketball training is vital to becoming the best player possible.
Physical Conditioning
Your off-season and even in-seasoning conditioning program pays off most in the fourth quarter. If you have the wind and the muscle strength to keep running, jumping and outplaying your opponent as the game is winding down, you can often take control of the action and turn close games into solid victories. This is something to think about as you're running miles and sprints and hitting the weights months before your season starts.
Skill Honing
The time between seasons is the best opportunity to work on parts of your game that need improving, or even add a new dimension to your game, like a crossover dribble or a better left-handed shot (for righties, of course). Think about the aspects of your game you'd like to work on and make a schedule that includes drills for those elements. Basketball camps can be great ways to get instruction in skills like ball-handling, shooting, rebounding and defense.
Team Chemistry
If you have the opportunity to work out with your teammates in the offseason, the bonds that form during running and weightlifting routines, as well as casual scrimmages, will pay dividends during the highs and lows of any basketball season. Knowing how hard each team member worked in the offseason will have everyone pulling harder together during close games in season.