Kris Humphries has been around the NBA long enough to understand how the business of the league works. So, when Humphries sat down with Nets general manager Billy King after the Nets saw their season end at the hands of the Bulls in the first round of the playoffs, he knew there was a good chance he’d be playing elsewhere next season. “I wasn’t surprised,” Humphries said Monday of being traded with his new Celtic green No. 43 jersey slung over his shoulder inside the Celtics’ practice facility in Boston’s suburb. “I talked to Billy after the season and just told him, ‘Hey, obviously I have an expiring contract, and I’m looking to play and get back in the swing of things that I was in before.’ “I guess it worked out for them, and hopefully it works out for me.” When the Nets re-signed Humphries as part of the spending spree last summer, part of the motivation of giving him a two-year deal worth $24 million (and split evenly over both seasons) was so that he could be used as the team’s major trade chip to upgrade the roster this summer, when sign-and-trades would no longer be an option for them because of the restrictions on teams over the luxury tax threshold in the new collective bargaining agreement. That decision turned out to work well for the Nets, as Humphries was a major piece of the financial math that made the blockbuster trade with the Celtics to bring Paul Pierce and Kevin Garnett to the Celtics possible. But for Humphries, the trade also represents a chance for a fresh start for him personally after a rough season in Brooklyn. Things started out well enough for him, as he averaged 7.9 points and 8.2 rebounds in just over 24 minutes a game in November as the fifth member of the Nets’ high-priced starting five. But Humphries was benched by Avery Johnson just before the coach was dismissed in late December, suffered an abdominal injury shortly thereafter and never again found a consistent role for himself throughout the rest of the season and playoffs, permanently starting spot and at times even his rotation spot behind Evans, Andray Blatche and Mirza Teletovic. “It was a tough situation,” Humphries said. “I don’t really look back and say this happened or that happened. “It’s the NBA, and a lot of different reasons for a lot of things that happen, but it’s a little frustrating we didn’t go further than we did with the kind of team we had, but it is what it is and I’m looking forward now.”