MIAMI — With three simple words that were more playful than derisive, Kevin Durant helped along the continuing reputation reset of a team that for much of its two seasons in present form has been the essence of entitlement and presumption. Dwyane Wade didn’t initially hear the remark after Durant effortlessly canned a second-quarter jump shot over Wade, though from Durant’s lips to television viewers’ eyes, the message was perfectly clear.  “Actually, I had to run down the court and ask him what he said,” Wade would say, taking no offense, acknowledging that it was not delivered in the manner of what most folks would describe as standard industry trash talk. Given the sheepish smile formed at the corner of Durant’s mouth, it was merely a statement of fact.  “You’re too small,” he told Wade again.  Well, duh, said the 6-foot-4 Wade, “he’s got seven inches on me.”  Officially only five, though exaggeration is most acceptable when confronted with Durant’s spindly and freakish length. In any event, the portrayal of the Miami Heat as undersized — to go along with undermanned — has apparently become part of the N.B.A. finals narrative, and LeBron James was thrilled to embrace the rewrite after the Heat’s 91-85 victory over the Oklahoma City Thunder on Sunday night provided a 2-1 series lead.  “I mean, size doesn’t matter,” James said. “It’s about just will and determination. It doesn’t matter if someone is taller than you or bigger than you or weighs more than you. Every last one of our guys plays bigger than what their height is, bigger than what their weight is.”  With a head of steam going to the basket, James has been a Category 5 hurricane blowing through the Thunder’s interior throughout the first three games. But suddenly the Heat have camouflaged themselves as the proverbial little guy, as the midmajor gunning for big game in the madness of March. More to the point, the superteam hubris of a year ago has given way to humility and respect for the extended playoff process, for what it takes to go all the way.  “Whatever it takes,” the Heat’s coach, Erik Spoelstra, said after his team overcame 37.8 percent shooting by winning the war in the paint — or what Spoelstra had earlier called “the line of scrimmage.”  Have the Heat ceded the high ground — or metaphorical air space — to their younger, longer, swifter opponents? A year ago Miami was the brash new thing, restless and relatively unchallenged in the playoffs until James and Wade woke up the veteran Dallas Mavericks with a premature display of grandeur in Game 2.  Now it seems the James-led Heat will happily play the role of the older and wiser hard hats, grasping the lesson that no team — not even the one that James bragged would win enough rings to fill almost two hands — is too big to fail.  “Well, really, every day we remind ourselves,” Chris Bosh said. “We think of that pain we experienced last year.”  They talk about “not drinking the Kool-Aid,” said forward Udonis Haslem, and of playing “48-minute games” and making sure no victory is celebrated unless it is the last one.  The Heat might have had good reason to believe last year’s finals were supposed to be more coronation than crusade. Miami stormed through the Eastern Conference, winning every series in five before taking Game 1 of the finals and seemingly coasting in Game 2.  Losing three straight and having the Mavericks win the title in Miami certainly humbled James — whose fourth-quarter disappearances were conspicuously damning — and the Heat. Falling behind in the series with the Indiana Pacers this year and having to survive an elimination game against the Celtics in Boston may well have hardened them.  Championship growth within the two-month playoff grind has occurred throughout history and most strikingly for some teams now characterized as the N.B.A.’s most cherished. Pat Riley, the Heat’s president, could speak with pride of how his brutish Knicks extended Michael Jordan’s Bulls to a seven-game, second-round slugfest in 1992 before Chicago won its second championship. James no doubt remembers his Cleveland Cavaliers taking the Celtics to seven games in the second round — and right after the Atlanta Hawks also went the distance with them — during Boston’s 2008 title run.  “It forces you to develop mental toughness and character, because nothing comes easy,” James Jones, the Heat’s reserve jump shooter, said. “You have to fight and claw for everything. It’s become a grind, and you either embrace it or you fail.”  Haslem added, “I think falling behind in a couple of series has definitely helped us find our recipe for success, and that is to play desperately.”  Along the way, it never hurts to get a little help from opponents and officials. In Game 2, Durant was victimized by a noncall when James elbow-checked him as he drove and shot for a tie in the dying seconds of a 2-point game. Sunday night, a fourth foul called after minimal contact — or less than James’s Game 2 physicality on Durant — with a driving Wade sent Durant to the bench in the third quarter just as the Thunder seemed to take control of the game.  Soon there came a flurry of missed Oklahoma City free throws, errant passes, regrettable shot selection and fouling of 3-point shooters — the Thunder playing like the 22- and 23-year-olds they are.  The series tilted toward Miami, but one defeat at home means the Heat must clinch in raucous Oklahoma City. In keeping with their new self-characterization, James insisted, “We know they’re not broken,” and added that Miami was only where it was last year after three games against Dallas, leading, two games to one.  Too big to fail? If anything, in this series, the Heat are on the diminutive side, too small to take anything for granted and from most indications better off for it.
The Miami Heat may have grasped the lesson that no N.B.A. team â not even one with LeBron James, Dwyane Wade and Chris Bosh â is ever assured of winning anything.