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It’s almost impossible to accurately quantify all the ways Marcus Smart makes the Boston Celtics a better team.

Sometimes that can be read as a dilemma—especially for someone drafted sixth overall by a franchise that can’t afford to miss on any of the prospects it targets—but it’s also not to say Smart isn’t valuable or even already a really good NBA player.

The numbers don’t glow—he’s averaging 10.0 points, 4.5 rebounds and 4.3 assists per game, with atrocious 35.9/29.4/55.2 shooting splits—but Smart oozes positive production (both subtle and obvious) that's noticed by those who watch him closely.

“There aren’t a lot of guys his age that have impacted winning the way he has,” Celtics head coach Brad Stevens said after Tuesday’s practice. “Maybe not from a statistical standpoint, but more so from: You can feel it when he’s on the court. You ask anybody in here and they all know Marcus’ value.”

Three years ago, Boston handpicked Smart to replace Rajon Rondo as its long-term franchise point guard, but the script quickly changed when it acquired Isaiah Thomas midway through Smart’s injury-marred rookie year.

Now 14 games into his third campaign, Smart is a titanium jackhammer off the bench. He does a little bit of everything, from running the offense as a traditional floor general to locking down opposing wings who are three or four inches taller than he is.

After a preseason game, one Celtics executive gushed to me about Smart’s impact. It was a game where Smart went scoreless in 13 minutes.

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His makeup is four parts Tony Allen mixed with one part Stephon Marbury (sprinkle a pinch of Troy Polamalu on top for good measure). That DNA is already unusual, especially in a league that prioritizes spacing, but Smart earns time on the court by packing unparalleled energy into just about every minute he’s active.

“I think toughness, generally, is difficult to quantify,” Stevens said. “Everybody brings their own levels of skill to the table and everything else, but you have to have a competitiveness and an ability to figure out a way to win that possession. And he’s able to do that on a lot of possessions.”

Even though Smart’s numbers have yet to swell, he’s developing while still contributing in ways that can’t be measured analytically. Here’s an example from one of Boston’s biggest plays of the year.

In an on-court interview that took place moments after he sunk the game-winning bucket, Al Horford immediately credited Smart for making something out of nothing. “If Marcus wouldn’t have ran in, I wouldn’t have got that tip.”

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So far as what can be measured, Smart’s quietly become an unerring conductor. According to Synergy Sports, the Celtics score 1.19 points per possession when he passes out of a pick-and-roll—a spectacular number. It’s a huge lift for Boston, a team that entered the season in need of reliable playmakers to replace departed free agent Evan Turner.

“He’s reading the defense a lot better, and he’s not rushing,” Thomas said. “He’s going at his own pace and really making the right play.”

Some of this is thanks to how Boston’s been able to space the floor. Smart can now weave bounce passes straight to the roll man without fear of a help defender squeezing in from the weak side. Last year, his options were limited. This year, he's in front of a buffet table.

“A lot of guys I’m playing with are a lot better than the guys I used to play with,” Smart said. “These guys are pros, so they’ve been here a while longer. They’re more experienced, they know what they’re doing and the floor is a little bit bigger. It’s opened up. There’s more space and these guys are knocking down shots. I’m just getting them the ball.”

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To mitigate his inconsistent outside shot (more on that later), the Celtics put the ball in Smart’s hands to let him operate with four knockdown shooters when going small with Horford at the 5, Jae Crowder at the 4, and Thomas and Avery Bradley as fellow guards.

“He’s gonna have the ball a lot in that group,” Stevens said. So far, the 22-year-old has responded extremely well.

Smart’s also driving deeper into the gut of defenses this year, forcing help rotations that then allow him to find open three-point shooters on the perimeter. He’s calm, nimble and precise. It’s ironic, because just about every other part of his game is total chaos.

Some aspects of Smart’s on/off numbers aren’t great—Boston’s offense is never better than when he sits—but those should improve as he spends more time with Horford, Crowder and Kelly Olynyk.

Boston’s defense, however, is much better when he’s wreaking havoc on its behalf. The Celtics force 12.9 turnovers per 100 possessions with Smart on the bench (a team low) and 15.7 when he’s active.

He currently ranks fifth among all point guards in Defensive Real Plus-Minus, a stat all the more impressive when you realize he’s a 6’4” combo guard who has to play up a position whenever Boston goes small (which is often). He often has to cover elite scorers like Andrew Wiggins, Harrison Barnes and Kawhi Leonard.

“It’s obviously not ideal for him to be a 3,” Stevens said.

But he’s a freak athlete—at the NBA combine, Smart’s standing vertical leap fell in between Zach LaVine and Aaron Gordon—who’s made a name for himself in big spots against larger players, most notably Paul Millsap during last year’s playoff series against the Atlanta Hawks. Smart holds his own, and it’s something players and coaches around the league really respect.

“He’s a good defender, very physical,” Leonard said. “It seems like he puts a conscious effort out there on the defensive end.”

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But he’s more than 220 pounds of immovable muscle. Few players navigate screens with more clarity than Smart. It’s almost impossible to dislodge him from his man.

“Smart plays hard, gets underneath players, makes a lot of steals, disruptions,” Golden State Warriors head coach Steve Kerr said.

It’s less exhausting to run a 400-meter dash atop Mount Everest than spend 30 minutes trying to score on Smart, but rugged play only travels so far in an NBA that requires efficient scoring. Smart’s true shooting percentage is one of the NBA’s worst among guards who’ve logged at least 400 minutes.

His free-throw rate is down and he’s struggling to finish around the basket. This shot chart is nothing but unpleasantness.

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But dig into the numbers and a few flickering reasons for optimism do exist. According to Synergy Sports, Smart is one of the best spot-up threats in basketball after he catches a pass off a pick-and-roll, averaging nearly 1.5 points per possession.

He’s yet to connect on a pull-up three, but he is shooting 35.2 percent on catch-and-shoot attempts and 38.5 percent when no defender is within six feet, per NBA.com. Smart shot a historically putrid 25.3 percent from deep last season, causing defenders to sag off and dare him to shoot.

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But when they do close out hard, he stays aggressive and drives the lane with a nifty bag of fallaways and floaters.

Few check off more boxes than Smart when it comes to the unquantifiable parts of basketball. Hustle alone can’t make up for a broken three-point shot, but hustle, surgical pick-and-roll play, bulletproof defense and devastating positional versatility make him irreplaceable.

More Unquantifiable NBA Players

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The reigning patron saint of esoteric contribution ever since he agreed to come off the bench in Golden State, Iguodala is the sticky glue that's held together some of the most dominant units in NBA history. The Warriors aren't able to unlock their Death Lineup without his two-way brilliance, astounding IQ and unselfish tendencies.

Paltry numbers haven't come close to reflecting his true worth (never more evident than when he tweaked his back during the 2016 NBA Finals), and the Warriors will once again struggle to win it all if Father Time prevents Iguodala from influencing multiple areas of the game as he has over the past couple seasons.

He isn't a star, but the 32-year-old allows stars to shine brighter than they normally would. That's valuable.

Cody Zeller

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Fresh off signing a four-year, $56 million contract, the youngest Zeller brother is boasting on/off numbers that mimic those of a superstar. His plus-12.7 net rating doubles the second-highest mark on the Charlotte Hornets, one of the NBA's most competent teams.

But Zeller doesn’t even play 24 minutes a game or attempt more than seven shots. He never posts up, and 57 centers have a higher offensive rebounding rate.

Instead, Charlotte's unsung hero influences the game by freeing teammates via some of the most effective picks in the league. According to NBA.com, he averages 4.7 screen assists per game. Kemba Walker and Nicolas Batum are thankful.

And despite harnessing a decent jump shot, Zeller almost always rolls hard to the basket, sucking in defenders on the baseline and freeing up opportunities for spot-up shooters behind the three-point line.

He's a sturdy positional defender and wears out lumbering bigs who can't keep up with him in the open floor. The Hornets are lucky to have him at that price.

Norman Powell

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Somewhat of a breakout cog in Toronto's quiet youth movement during last year's postseason, Norman Powell isn't unquantifiable so much as he's underutilized. The 23-year-old hasn't even played 200 minutes this year despite making 46.2 percent of his threes and hardly ever turning it over.

Toronto plays faster when he's on the floor and its offense sizzles.

But Powell also tends to over help on defense, drifting away from his man when he should stick close by. He's also only 6'4"—too small to harass most wings. So despite playing a vast majority of his minutes beside Kyle Lowry and DeMar DeRozan, that trio has cracks on defense.

Still, Powell is solid. And it's probably in Dwane Casey's best interest to get him on the floor as often as he can.

All quotes in this article were obtained firsthand unless otherwise noted. Statistics courtesy of NBA.com and Basketball-Reference.com and are accurate as of Nov. 30.