Tyler Zeller was a mere afterthought when the Boston Celtics acquired him last summer, but GodZeller is quickly becoming a fan favorite due to his knack for hustling up the floor, rolling down the lane, and scoring efficiently near the rim. However, the 7-footer is actually earning his minutes with the Celtics by excelling on the defensive end of the floor.

"Just continue to be a great presence for us defensively," coach Brad Stevens said when asked about what Zeller needs to do to make an impact. "I think he's added to our team in that way. And I don't know that I would've said that when we first got him here. He's really gotten better on the defensive end of the floor. And in fairness to him, he's played in three different systems in three different years for three different coaches."

Situation matters and Zeller's young journey in the NBA hasn't been easy. The product of North Carolina has never been able to mature in a system, nor has he received a consistent role until this season with Boston.

Zeller excelled as a rookie with the Cleveland Cavaliers, averaging 7.9 points, 5.7 rebounds, and 1.2 assists per game. However, after a coaching change and an emergency appendectomy on the eve of his sophomore season, Zeller saw his role decline. Cleveland then found him expendable after the return of LeBron James, and he eventually landed in Boston.

Studying Tyler Zeller

Tyler Zeller gained 15 pounds after working on his core strength over the offseason, which has paid off dramatically, since he has transformed himself into a highly reliable defensive player. Zeller has career-highs defending the pick-and-roll and post-ups, according to Synergy Sports Technology.

Zeller ranks as the 18th-best big man in the NBA defending post-ups (with a minimum of 1.5 possessions per game). This is area the Celtics have otherwise been steamrolled this season, as Synergy has them rated as the 23rd-worst team at defending on the low block.

By default, TZ has frequently been tasked with defending behemoths like Roy Hibbert, Dwight Howard, and Marc Gasol, and while the results haven't always been exceptional, his impact has allowed the Celtics to stay afloat defensively, with a 103.2 defensive rating, good for 14th in the league.

Zeller does a decent job of initiating contact with the ball handler and steering them into "no man's land." Or if they do get to their desired positioning, Zeller usually is successful in getting a hand in their comfort zone. If TZ continues to add strength, especially to his lower body, and plays with the same level of intensity and fundamentals that he currently possesses, then he could certainly make even more significant strides next season.

Boston's Achilles' heel this season has been their pick-and-roll defense, as opponents are typically able penetrate the lane, draw help defenders, and then kick it out, where ball movement naturally finds the open shooter.

But the chunk of the blame really can't be blamed on Zeller, who has been serviceable at protecting penetration from reaching the rim, which is where the most advantageous shots occur.

Zeller's pick-and-roll defense numbers on Synergy are right around the league average, but that is largely due to the fact Boston drops or "ices" pick-and-rolls, which encourages opponents to shoot threes. However, the Celtics big man is shining according to other metrics.

Vantage Sports records a statistic called "Keep-in-Front %," which measures the percentage of drives a defender stays between the opponent and the basket. Zeller ranks 3rd in the NBA with an 84.5 Keep-in-Front %, which supports the assertion that his defensive success is largely due to his sound fundamentals. The league average for all big men is 68.9, according to Vantage Sports, which means Tyler Zeller is elite in this category.

Zeller is not a shot blocker, averaging only 1.3 blocks per 36 minutes, which ranks 64th in the league, but he makes up for it by keeping himself between his man and the basket. This action is exactly what prevents many shots from ever occurring, which is the topic discussed in Eric Weiss and Kirk Goldsberry's 2013 study, "The Dwight Effect."

In that paper, Weiss and Goldsberry creatively evaluated how bigs disrupt shooting patterns of the opponents, not by blocks and steals, but by having their sheer presence on the floor to make "invisible plays" that don't show up on traditional stats sheets.

Zeller is by no means a player that opponents "fear" simply due to name or reputation, but new advanced statistics from SportVU -- which were clearly influenced by the Weiss and Goldsberry study -- do suggest that "The Tyler Zeller Effect" is a real thing for the Celtics.

Shooters are hitting just 47.2 percent of their shots at the rim, according to SportVU, which ranks 22nd for all qualified players. This is not a lofty number, but it is significantly better than the 119-player sample's average of 50.9 percent. To put that into perspective, TZ allows 0.944 points per shot at the rim compared to the 1.02 points per shot of the average player.

In the examples above, Zeller is able to disrupt shots by using proper body positioning and technique when contesting shots. This has been a consistent theme throughout the season when he's challenged at the rim, which has been key for the Celtics to remain competitive in so many games, though they have ultimately fallen short.

Let's continue digging deeper and look at Seth Partnow's Rim Protection Value stats from Nylon Calculus. Partnow devised a stat that derives from SportVU data called "Points Saved/36," which is how many more or less points per 36 minutes a player prevents with their rim protection than an average NBA big man.

Zeller ranks 8th in the NBA with 2.26 points saved per 36 minutes, according to Partnow's statistics as of January 13. Here is how Zeller compares to Nylon Calculus' top 10 defensive bigs, sorted by Points Saved/36, using SportVU statistics, as well as some advanced data courtesy of Synergy:

Tyler Zeller fairs well compared to his counterparts here, which includes studs like Roy Hibbert and Rudy Gobert. Zeller ranks in the top half of the grouping for Synergy Sports, and about average in all SportVU metrics, but he is the lone player with fewer than 2 blocks per 36 minutes. Even though Zeller is not a shot blocker, he has still been as effective as they are.

Some names on that list might be surprising, like Hassan Whiteside and John Henson, so you might be wondering if Zeller's success is just a fluke. So, let's see how he compares to 10 big men that are often considered the best rim protectors in the NBA due to their productive histories and their reputations.

Once again, Zeller compares extremely favorably, ranking near the top of every category except for blocks per 36 minutes. Of course, some of the great defensive bigs play most games against the Western Conference, like Marc Gasol and Dwight Howard, so their numbers could be skewed playing against equally-talented players, but the point is to show that Zeller does stand up to these players statistically. In other words, these comparisons aren't being made to say that Zeller is better (or worse) than any of the listed names, but that he deserves to be recognized for his success and development as a defensive player so far this season.

Assessing Tyler Zeller's Future

The Boston Celtics are average as a whole defensively, but Tyler Zeller is not. The big man is an asset that can't be overlooked when assessing the state of the Celtics, because for all the talk about needing to find a rim protecting center, they might just have one on their own roster.

It's easy to forget that Zeller turns just 25-years-old this month, and that he has yet to play for more than a full season in a single system. Zeller still has plenty of room to grow on both ends of the floor, but especially defensively, where additional bulk while maintaining quickness could take his game to the next level. Big men often take longer to develop than other position in the NBA, so for him to even be performing at this level at this stage of his career is remarkable.

Tyler Zeller might not be the preferred long-term starter at the center position for the Boston Celtics, but if the front office is unable to find one of those truly unique and elite bigs, then they should still be able to build a contender with GodZeller in the starting five.

Kevin O'Connor can be contacted on Twitter @KevinOConnorNBA or by email at KevinOConnorNBA@gmail.com. Thanks to shnts07 over on Celtics Reddit for the inspiration on the comparison section. For my articles on Zeller before he was hot, click here, here, and here.

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