This piece was originally published on Dec. 2. It is being republished as part of SB Nation's series on the best role players in the NBA this season.

The man who's done the most to change the fortunes of two NBA teams is a lumbering 31-year-old big man who can't leap over a piece of paper, pump-fakes more than a drinking bird and shoots jumpers like he's aiming at a dart board.

His name is Zaza Pachulia, and he seems to fit the profile of a typical NBA journeyman. An anonymous second-round pick in 2003, Pachulia broke in with the Milwaukee Bucks, enjoyed a decent career as a backup big man and cult hero with the Atlanta Hawks, returned to Milwaukee and is now anchoring the middle for a Dallas Mavericks team that's somehow 11-8 despite an aging, shallow and injury-riddled roster. Meanwhile, Pachulia's former team is floundering despite the addition of maximum free agent Greg Monroe and the healthy return of 2014 No. 2 overall pick Jabari Parker.

The cold numbers show the output of Pachulia's process. Last year's Bucks were seven points better per 100 possessions with Pachulia on the floor. With Pachulia gone permanently this year, the Bucks are six points worse overall and a whopping 10 points worse on defense than their mark with Pachulia on the floor in 2014-15. There are other reasons for this -- the loss of fellow film room All-Star Jared Dudley, the addition of defensive sieve Monroe, the slow recovery of Parker disrupting the rotation, the injuries to key bench players -- but none are bigger than Pachulia's absence.

Meanwhile, the Mavericks' output is also significantly better with Pachulia in the game. Dallas outscores opponents by 3.5 points per 100 possessions with Pachulia in and are outscored by two points per 100 possessions with him out. The impact of those numbers is felt on both ends.

These trends have everything to do with the man the Mavericks acquired for a 2018 second-round pick that the Bucks will never see. Pachulia's success isn't measured through his production, though he is gobbling up rebound after rebound. His success is measured by ticking off all the intermediary steps on a checklist for a successful NBA possession while letting teammates finish the job.

Defense is Pachulia's calling card. He maximizes his limited gifts with ideal positioning of his feet, arms and hands. Like many big men, he hangs back when defending a guard on a pick and roll, but he walks the tightrope of contesting the pull-up jumper while giving himself space to cut off the drive. This also allows him to seal off the basket while coming out to shooting big men if needed.

That preparation makes up for a lack of foot speed. Zaza shouldn't be quick enough to cut off this Mike Conley pick-and-roll and also rotate back to Marc Gasol, but he gets it done because he puts himself in position to complete the fewest defensive slides possible. He also has quick hands that he uses to slap down at the ball without committing silly reach-in fouls.

Pachulia doesn't complete this play alone, and that's the point. He's a cog in the Mavericks' defensive machine, and no cog fulfills his specific duties better. Even the subtle motion to recover to Gasol with his hands up serves a purpose. It cuts off Gasol's passing lanes and forces him to think for just an extra second before shooting.

Monroe, by contrast, is poorly positioned and lead-footed in similar situations. The contrast between Pachulia and his replacement in Milwaukee could not be sharper.

Pachulia's also a master in the art of two-nineing, a practice where big men help off their men to clog driving and passing lanes for just long enough to avoid a defensive three-second call. He plays free safety flawlessly, shutting off countless potential openings and ensuring he doesn't need to move far to address a threat.

For a big man who can't jump, Pachulia sure alters a lot of shots at the rim. Opponents are shooting 49 percent on shots inside of five feet when Pachulia is defending, per NBA.com player tracking data. That's a respectable mark that's significantly better than outgoing Dallas center Tyson Chandler and barely worse than DeAndre Jordan, the big man Dallas really wanted this summer.

Pachulia stays vertical, gets his body in front of drivers and avoids fouls. Despite his reputation as a hacking goon, he averages the same number of whistles per 36 minutes as Tim Duncan. He's sneaky, too. He'll lodge his arm on a driver's body to ward them off, only to pull his body back just as they try to jump into him, causing them to flail off-balanced. That trick fooled James Harden, and it's hard to fool James Harden when he's searching for contact.

Yet Pachulia's defensive prowess, while understated, can at least be comprehended. How the hell does a player with no post moves, limited shooting range and YMCA-level athleticism help a team so much offensively?

By using two overlooked body parts: his chest and his rear end.

The chest is for setting screens. When Pachulia sets a screen, he really sets a screen. Perimeter defenders can't get around him because his base is so wide and his angle is exactly what his guard needs. Screens create openings, which in turn create open shots.

The numbers back this up. Deron Williams' true shooting percentage is more than 15 points better with Zaza in, per NBAWowy. Wes Matthews' is 11 points better. Dirk Nowitzki is deadly no matter what, but even he's two points better with Zaza in the game. Dallas has plenty of scorers and Pachulia gets them open.

Milwaukee also has plenty of scorers, but it no longer has anyone to get them open. The slumping Khris Middleton badly misses Pachulia on those baseline screens that are the core of Milwaukee's half-court attack.

Pachulia is especially slick setting flare screens when defenders are focused on the ball.

He'll even screen a recovering defender to prevent them from rotating over to stop a drive or open shot, a trick only a handful of other centers use.

The rear end is for Pachulia's most obvious skill: rebounding. He's 11th in the league in rebound percentage and is coming off a 21-rebound performance against the Portland Trail Blazers. He's the platonic ideal of the fundamentally sound big man your youth coach wished you could be. He sneaks into the areas where he knows the rebound will fall, then backs his ass up to root opponents out of them. That ensures a teammate will get the rebound even when he can't himself because he can't jump over my laptop.

The Bucks, meanwhile, are dead last in the NBA in rebound percentage. Monroe snares many rebounds himself, but the Bucks only secure 46 percent of them as a team and an awful 68 percent of them on the defensive glass. When Pachulia was on the floor last season, Milwaukee grabbed 51.5 percent of all boards and nearly 76 percent on defense, specifically. Suddenly, Milwaukee's army of high-flyers don't have the free space Pachulia's rear end once created to swoop in and grab the ball. It's no wonder the team can't rebound anymore.

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Pachulia shows there's still value in the dirty work, provided a player actually has the intelligence and craftsmanship to pull it off. In Dallas, a collection of one-dimensional scorers suddenly looks whole. In Milwaukee, a swarm of lanky jumping jacks suddenly looks disorganized. A career seven-point, six-rebound player really does make that big of a difference.

This is why Mark Cuban was so excited to acquire Pachulia when he missed out on Jordan. This is why a man that looks more like an intimidating bouncer than a basketball player has dramatically changed the fortunes of two franchises at once.