Here's the thing:
At some point, in the NBA, it's not about what you COULD do. It's about what you DO.
Vince Carter could have been as good as Kobe Bryant. But he isn't, and wasn't--it's not about ability, it's about execution.
Green isn't some rook. He's been in the league for four years. If he were lighting it up while he was in the game, I'd be screaming about him needing more minutes too. Stop blaming other guys--every player has to step up and perform for himself.