To this point, the Celtics have had to muck their way through the competing agendas of their own players and now have a layer of outside interference from those of us in the media that is attached to the trade deadline and will linger beyond.Still, they’ve won nine out of 10, and that’s Stevens’ job. The Celtics are third in the conference and within five games of the first seed in the East.But the trade deadline and the upcoming free-agent extravaganza will weigh heavily on Boston, and whether Stevens likes it or not, he must keep his team together through it. MORE: LeBron James addresses Irving’s apology callThankfully, for Stevens’ sake, the Celtics pushed off the Thunder long enough for a win, Boston’s ninth in its last 10 games. The Celtics go to Cleveland on Tuesday, and should continue their winning ways.But there’s much more at play than the schedule. The Celtics are a team eager to push through the coming week and the passing of Thursday afternoon’s trade deadline, which will be topped that evening by a visit from the Lakers, the team at the eye of just about every NBA storm these days.Few will be happier than Stevens, who has been the Celtics coach since he was plucked from Butler in 2013 to oversee the post-Doc Rivers rebuild. Stevens has proven himself as a coach in the intervening years, but it’s not until now, in his sixth season, that he is truly being baptized in the NBA’s turbulent waters.Stevens’ handling of the various Celtic controversies this season has mostly gone overlooked. Irving’s locker-room leadership has come under fire, but leadership needs to come from the coach, too. That’s not Stevens’ strong suit. Past Celtics veterans have said that Stevens tends to handle his players with too much emphasis on Xs-and-Os and not enough TLC.Indeed, Stevens, at least publicly, has approached the team’s various controversies with a shrug of the shoulders and a stiff upper lip. But how he holds this roster together will be his greatest NBA test to date and will go a long way toward determining whether Boston can truly contend for a spot in the NBA Finals this spring.Stevens has given stock answers to questions around his team all along. Last month, in the wake of the tussle between Celtics forward Marcus Morris and Jaylen Brown, Stevens said, “I’m not going to get into that. Ultimately, my focus is to on how we’re playing on the court.”He’s stuck with that line. The latest go-round on the Celtics’ drama-rama has been the rumors of Irving potentially bolting Boston, perhaps for the Knicks (who bleached their payroll last week with the trade of Kristaps Porzingis) or the Lakers. Further, the Celtics’ presumed offseason pursuit of Davis has been under assault from Davis’ agent, Rich Paul, who also represents LA star LeBron James and clearly wants Davis to play for the Lakers. Paul went so far as to trot out Davis’ father to ESPN — the senior Davis lambasted Boston for its treatment of Thomas, traded by the Celtics two years ago.In New York, Stevens told reporters, “I think that’s just part of being in this league and being in professional sports. Ultimately that’s our job, is to block out everything and make sure we understand what we need to do well to have success. And so it’s about focusing on the possession at hand and literally staying in that moment, and that’s really challenging.”There are a lot of things in human nature that pull against that, but I think the very best teams and the very best players all are able to do that and that’ll be the task.”TRADE RUMORS: Is Anthony Davis trying to scare off Celtics?On-court player scuffles, individual agendas, locker room turmoil, incessant trade rumors, star free-agent chatter — the Celtics have had all of the above in the past two months. That’s a new development. They certainly don’t have these sorts of tribulations in the Big East. Before this season, Stevens was blessed with overachieving players and low expectations, and for a new guy taking over a historic franchise, that’s about as happy a situation as you could expect.That’s allowed Stevens to build on the same underdog reputation he had at Butler, which he took to the NCAA championship game twice. He’s never entered a season as a frontrunner, but he’s succeeded anyway. By the end of his second season in Boston, the Celtics were a playoff team, despite having erstwhile center Tyler Zeller as the roster’s top-ranked player in win shares.The following year, Stevens won 48 games with a primary starting five of Isaiah Thomas, Avery Bradley, Jae Crowder, Jared Sullinger and Amir Johnson. Last spring, Stevens shocked the East by again getting to the conference finals — without injured stars Kyrie Irving or Gordon Hayward — coming within a game of the Finals.Along the way, Stevens was exalted in Boston. His rotations were unquestioned. His ability to develop players, whether bringing along Jaylen Brown slowly or throwing Jayson Tatum quickly into the NBA fire, was proven. His out-of-timeout plays were hailed as masterworks of art by the Twitter faithful.But NBA coaching is part Dr. Naismith, part Dr. Phil. Stevens has not had to play the psychoanalyst much with the Celtics. He has not had to defuse locker-room discord. That’s been the undoing of the bulk of NBA coaches over the decades, and it has been especially difficult for coaches from the college ranks, where coaches wield so much more power. BOSTON — By the time the Celtics took the floor here at TD Garden on Sunday afternoon, coach Brad Stevens looked at ease, finally.Nevermind he was preparing for the Thunder, winners of seven straight games. What mattered was that the Celtics were back among their home fans and all the kerfuffle that engulfed the team in the last few days, all the questions about Kyrie Irving and Anthony Davis and Isaiah Thomas (yes, him again), could be safely filed away for a few hours.