Jeff Green was often at his best last season without Kevin Garnett and Paul Pierce on the floor. Those were times when the Celtics forward couldn’t give into his natural inclination to defer or depend on his more celebrated teammates. Well, Green knew the parameters were going to change. Not to this dramatic degree, probably, in the wake of a franchise-altering trade that has sent Pierce, Garnett and Jason Terry to Brooklyn. But Green sounds ready for the next step in his development, when his leadership is going to be scrutinized. That, anyway, was the spirit he carried into Orlando’s practice facility yesterday morning. Along with teammate Courtney Lee, Green took a seat next to new coach Brad Stevens and let the new era soak in. Stevens’ fresh perspective has Green excited. “We had a chance to talk about the style of play we’re used to,” said Green. “We just talked about the game itself, and got to know each other a little more off the court. I think we’re developing a great relationship right from the start. . . . We’re going to be in a great position to showcase what we can do. A coach like Brad is going to put us in a great position.” Here’s what doesn’t seem to bother Green: the remarkable upheaval in the organization over the last month. Coach Doc Rivers, Pierce and Garnett, three individuals pivotal in his career over the last 21⁄2 years, have been replaced by a youth movement. “It’s the NBA. It happens,” he said. “I won’t say I was surprised. I wasn’t shocked. I’m happy. It’s a great start. Trades happen. Coaching changes happen. I’ve had a coaching change early in my career, and I’ve been traded. You move on and take the opportunity with the players and the coach that you have. You can move forward and be positive. “Now it’s time for the other guys to step up. We have (Rajon) Rondo, who has won a championship. He knows what it takes to win. We have myself, who was part of a 50-win team in Oklahoma. Kevin and Paul taught me the ropes to be a leader. I’m ready for the challenge, and I’m sure that Courtney and Avery (Bradley) will also be ready to step up and be more vocal.” Green admittedly is about to lose his security blanket in Garnett, who focused on empowering Green last season. When Garnett said Green had the potential to be one of the best players in the league, he was genuinely touched. “They were big in my process. Just mentally Kev started me out to be a more vocally active type of player, a leader by action, not on his level, but in my own skin and my own way,” said Green. “I owe that to him for my growth in the game. He’s done a lot for me on and off the court. He’s a guy I looked to, who helped me to get to this position. A lot can be owed to him. “First of all, I’m happy for them. When you have great veterans like a Paul, JET (Terry) and KG, you want the best for them. It’s sad to see them go, but I’m happy for them. Brooklyn is a lucky team, but we’re competitors. We look at this as a chance to prove people wrong. We’re still a great team.”