There's a delightful contrast between Justise Winslow's game and his personality. On the one hand, the 19-year-old Heat rookie's game is loud. He needles opposing team's top wing scorers like an annoying little brother. He accepts the mano a mano defensive battles against the league's very best players, then makes them look helpless with everyone watching. He also has a knack for making the big play at the precise moment the game reaches its crescendo.

On the other hand, does Winslow ever smile? Every positive sequence, whether an isolation defensive victory, coast-to-coast layup, timely rebound, smart cut or even correct defensive rotation, ends with that same stone face. From one perspective, Winslow's calmness shows a maturity beyond his years. From another, his iciness is an intimidation tactic that unnerves even the steadiest opponents.

As Erik Spoelstra told Sports Illustrated, Winslow has the "emotional stability" to thrive. Right now, that's more important than having the jump shot and, if you look closely, just as demonstrable a skill. Winslow's willingness and ability to succeed at non-glamorous tasks are an impressive combination most 19-year-olds simply don't possess. Better yet, they're turning Winslow into a star.

Individual defense has been Winslow's hallmark from the jump and it didn't take long for the league to notice. Winslow accepted the DeMar DeRozan assignment in his seventh pro game and thoroughly smothered him, forcing half a dozen errant shots and turnovers in a decisive second-half run.

Other top scorers soon learned that scoring on Winslow is no picnic. Jimmy Butler found out in cruel fashion in the final minute of a crucial January game.

Most good defenders are either quick or sturdy, but Winslow is both. He can slide his feet to cut off quicker players, yet is also strong enough to prevent scorers from overpowering him on drives. They can't get around him and they can't go through him.

It doesn't matter if Winslow's defending a jet-quick guard like J.J. Barea or a strong post player like Dirk Nowitzki. He can make both look terribly uncomfortable in the same game. (Ignore Luol Deng's block at the end of the second clip. Winslow did all the hard work to set that up).

While some of Winslow's skills come to light in plain view, others are camouflaged in the weeds of a normal possession. If you're wondering why your team's star player can't get the ball in a good position against the Heat, it's probably Winslow's fault. Kevin Durant found that out in early December.

It's incredibly difficult to screen Winslow, because he's dogged in his pursuit and possesses excellent footwork when chasing his man off the ball. He knows all the angles and when to use them, which explains why he knew to shoot the gap in the above clip. There are times when it seems like he has a magnet on his man.

There are other times when it seems like he has a magnet on a teammate's. Many other rookies entered the league flashing the requisite one-on-one defensive tools, but precious few, if any, understand off-ball rotations, helping the helper, proper switch timing and all the other nuances unique to the pro game. The Heat are more than six points better per 100 possessions defensively with Winslow in the game, and that's not only because of those obvious possessions against other stars. It's also because of Winslow's ability to spot a threat, address it and then get back and carry out his normal assignment.

Most rookies need time and repetition to process these quick decisions in real time. No level of basketball prepares them for the speed of an NBA possession and the mental fatigue of competing against the world's best athletes for 48 minutes again and again and again. They inevitably get distracted by shiny objects elsewhere on the play, skimp on an overlooked task or reach lazily when they should move their feet.

That rarely happens to Winslow. When Spoelstra says Winslow has "emotional stability," he's referring both to Winslow's external and internal calm in the face of the intense pressure of NBA defense.

That's not to say Winslow's game is perfect the way it is, since offense is still a major work in progress. Winslow is shooting just 26 percent on three-pointers and a ghastly 31 percent outside of five feet. He shot quite well from the college three-point line at Duke, but has struggled mightily to adjust to the longer distance in the NBA. He bends his knees too early, his shooting motion is far too stiff and it's a mystery where his feet will land once he's done, especially when he must shoot under duress.

Because of his perimeter struggles, the Heat often must play Winslow at power forward to get more shooting on the court elsewhere. Increasingly, teams give Winslow the Tony Allen treatment, leaving him alone to help on the other four Heat players. On this play, for example, Winslow is being "guarded" by Clippers center Cole Aldrich. He predictably missed the ensuing open three.

That aside, though, Winslow does have a few important offensive talents. He's a terror in the open floor, capable of snagging a defensive rebound, shifting into attack mode and sliding around and through any obstacles. That's particularly important to Spoelstra's recent mandate to increase the team's pace. The Heat average two and a half more possessions per game with Winslow on the court; only Deng's presence makes close to that much of a difference.

Cutting to the basket when appropriate is another key Winslow skill. Much like mentor Dwyane Wade, Winslow compensates for his lack of a jumper by darting to the rim at the opportune time. He doesn't just rush in the second he's ignored. Instead, he waits for his teammate to create the right angle and catches opponents leaning at the wrong time. He has a knack for timing that's far beyond a player with his NBA experience.

Those attributes alone won't make Winslow a good offensive player. He must fix that shot and he must show his ball-handling and playmaking abilities when given the chance. (Early returns are promising, but few). But as the time-honored cliché goes, he's good at stuff you just can't teach. Yet again, Winslow's "emotional stability" can be reinterpreted as actual basketball skill.

At the same time, that Spoelstra-ism -- the stone face during the game's loudest moments, combined with the commitment to thrive during its quietest -- also provides the biggest reason to be optimistic about Winslow's future. There's no better disposition to have when trying to improve a jump shot or tighten a handle. If Winslow is as emotionally mature as Spoelstra says, he'll attack those workout sessions with incredible vigor. If he fails to improve, it won't be because he left a stone unturned.

Once those skills come, the sky really is the limit. Winslow may be a part-time player now, but his game, accomplishments and on-court intelligence are already ahead of other overlooked prospects like Kawhi Leonard, Paul George and Jimmy Butler at the same age. When Leonard, George and Butler were 19 going on 20, they were shooting 29 percent from the college three-point line, toiling away on a terrible Fresno State team or barely playing for their school at all. They had the right emotional stability, ultimately fixed their weaknesses and are now three of the best wing players in the NBA.

If Winslow follows a similar development path, he could be the best of the bunch. Just don't expect to see him getting too excited about it.

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