In the competitive world of athletics, players and coaches tend to forget sometimes that they are not at the center of the universe. Coaches tend to think they are Dr. Naismith from time to time and players lose sight that the team is more important than they.
As a player, I don't care how great of shape you are in, but you won't play whole game. I know it's disappointing that you get taken out of the game, but you just can't play the whole time. Especially if you have a team with some talented players.
Some players are better at some things than you are and how games get played out will decide if you can play or not. Some situations call for more ball handlers, shooters, rebounders, or defensive players. Being substituted out for doesn't mean you did anything wrong or that you haven't done your job, or that you are in trouble. Often, it is to get someone who is better than you at something into the game.
If you make mistakes, you will be taken out of the game. Period. If you don't like that it is a possibility, quit and go do something else. Quit moping, mouthing, and looking into the stands because....
Negative body language is embarrassing. It is an embarassment to you, the team, the coaching staff, and if you are my child...to me. Do not draw attention to yourself with slouching shoulders, a sullen look on your face, talking under your breath, talking negatively to your teammates, or moping on the sideline. Just stop it.
Be a selfless teammate. If you can do that, if you can at least act happy about the success of your teammates, it will build team cohesion.
Finally, most of all, quit questioning everything. A mature coach will ask your opinion from time to time about certain aspects of the team and the game, but that doesn't mean you get to coach. You will be coached, and you need to buy into the game plan and the coaching staff.
If a team does understands the above, they will be successful. Understand the above and have some talent...the sky is the limit and you are setting a positive example for those watching.
Don't do the above and you will not live up to your potential and you pass on a legacy of negativity to those who come after.