NBA stars are defined by the number of championships they win, and every player's title window closes at some point. Therefore, it's crucial for today's aging stars to take advantage of every opportunity they have to win one final title.
While it's obvious when the window closes in certain situations, that isn't always the case. The past couple of seasons for the Boston Celtics are the perfect case study, as GM Danny Ainge decided to keep his core together in order to make a couple more title runs.
Did the Celtics' title window close after being eliminated by the Miami Heat during the 2011 playoffs?
The answer is probably not, as Boston pushed the Heat to seven games the following year. With that said, who knows what the Celtics' future would hold if Ainge decided to retool his roster in order to solidify the team in the post-Kevin Garnett/Paul Pierce era?
Title windows can close for various reasons, with injuries and lackluster teams being two common ones. Two teams are represented multiple times, which speaks to the pressure for each franchise to win now.
The players on this list all had wonderful careers and are leaving the NBA in better shape than they found it. Not everyone on this list is set to retire in the immediate future, but their title windows are closing fast.