The Washington Wizards are 7-25, and when you're 7-25, there aren't really many players you can define as "game-changers." Well, there are plenty who change the game, but for the worst. Something tells me that's not your idea of a "game-changer."
If I had to pick one player on the Wizards, though, I'd probably pick Trevor Booker. Did you know that only six rookies and sophomores who would qualify for the minutes title have a higher PER than Booker this year? If you didn't know, you know now. Nobody would say Booker is a better player than Ricky Rubio, for example, but it does show he's really developed as a role player for this team.
Obviously, Booker has his faults. He's still a very poor jump shooter, shooting only 29 percent from the field from 16-23 feet. He gets physically overwhelmed every so often by big players, and while he defends his man well, he's still susceptible at times when defending the pick and roll. Let's not go proclaiming Booker as a superstar player yet.
But we can safely say that Booker is a piece the Wizards could use going forward. If he can improve that perimeter jump shot, he can solidify a spot as the Wizards' long-term starting power forward. If not, he'll always be a productive bench player that can come in and change games with his foot speed and toughness.