Known more for his outbursts than his occasional hot shooting hand throughout his career, Cavaliers guard J.R. Smith is doing his best not to be a bad guy this postseason.[...] the volatile Smith, on his third team in five years, knows this is his moment in the sun — playing in the NBA Finals with LeBron James, the best player in the league.[...] Smith has burned bright off the bench, posting games of 28 points (including eight three-pointers) and 18 points against the Hawks in the Eastern Conference Finals."J.R. can go off and make eight threes anytime," Warriors coach Steve Kerr said.Smith, who won Sixth Man of the Year honors in 2013, is averaging 13.5 points and shooting 40 percent from three-point range in the playoffs.James wanted a long-range shooter with a quick release and an endless supply of confidence, and didn't care about Smith's on-court and off-court transgressions.The Knicks were so desperate to unload Smith that they included Shumpert, who has become the Cavaliers' second-best defender behind James."For me, as a leader of a team, you always just want to try to give someone an opportunity," James told reporters.The Cavs were 19-16 when they made the trade,...