Barbosa has potential. I think that someday he can grow into a player who can average 17-18 points a game as the third/fourth option on a team, shoot 40% from 3 point range every season (and even in a postseason while going through a prolonged shooting slump), teach younger players about hard work, professionalism and off-season/pregame work (changing a team's culture as much as a guy defending in a panther stance and headbutting the basket before games), be a Finals MVP runner up, become one of top ten career free throw percentage, and be one of the classiest players of his generation.
When you see potential like that, you trade for it, no matter what you give up.