Make sure to check out Part 1 and Part 2 first.

Section 4: Causes of the Shift

The main causes of this transformation are the various rule changes which the NBA implemented over the course of the past several decades. I will break these down into offensive rule changes and defensive changes. 

4.1: Help and Zone Defenses

In 2000 the NBA introduced two major defensive rules that would cause a shift in what abilities were most desireable in defenders. One of these changes was legalizing help defense. Previously, defensive players were required to be guarding an offensive player; they couldn’t just stand in open space. This prohibited many of the defensive schemes which are employed in today’s NBA — including anything involving zone or with leaving a help defender as a second line of defense — as a player had to stick to guarding his man or be fully committed to double-teaming someone else: a risky move since it would leave the original man wide open. Not only did this prohibit help defense, but it made it illegal to use zone defense, essentially forcing teams into playing man-to-man defense. These circumstances were favorable for big men who wanted to post up. They would most likely just have to beat one player, and if someone was to double team them, it would mean that a teammate would be left wide open. With these old rules, the offensive team could draw defender further from the basket just by spreading out themselves and leaving one or two guys in the middle to post up. Teams were now able to keep the paint packed on defense, making it harder for offensive players to post up and score.

Here Orlando Magic center Biyombo (rightmost) is playing help defense in the post, meaning that even if the New York Knicks player Kristaps Porzingis gets past his primary defender, he will still face a shot blocker in the paint. However, since Biyombo is allowed to help instead of double teaming, he can still rotate to a player in the opposite corner if Porzingis passes to someone else. This type of defense makes posting up harder for offensive players, and it has only been allowed for less than 2 decades.

Here the Miami Heat are able to use a scheme on defense that was once considered illegal. Everyone that isn’t guarding the offensive with the ball is inside of the paint, ready to make it much more difficult for anyone to score in the interior. Even though the Heat’s players aren’t actively guarding an opponent, they have strategically positioned themselves in a manner that allows them to switch out to an opposing player if they receive a pass.

4.2: Rules Directly Attacking Post Ups

While plenty of rules have indirectly led to decreases in post ups, there also have been multiple rules with no purpose other than reducing post ups in the NBA.

4.2.1: 5 Second Back to the Basket Rule

The 5 second back to the basket rule added in 1999 has been the most flagrant attempt by the NBA to wipe out post ups.

An offensive player in his frontcourt below the free throw line extended is not allowed to dribble the ball with his back or side to the basket while being actively guarded by an opponent for more than 5 seconds.

This quite literally puts a 5 second time limit on posting up, and it can only be explained by the NBA not wanting players to be posting up, as the rule has no other noticeable effects. Before this rule, post ups could take 10 to 15 seconds with NBA players trying to take full advantage of their strength to get in the most optimal position by simply outmuscling the opponent. However, this severely restricted what could be done in a post up, and is one of the main reasons for both the decline of post up frequency and efficiency.

4.2.2: Widening the Lane and the 3 Second Rule

The NBA has had the 3 second rule for a long time, dictating that no offensive player can stay inside of the lane for more than 3 seconds at a time. This not only forces the offensive player to act quickly once he happens to get into the lane, but worse, it makes it much harder for the offensive player to wait for the ball while staying near the basket.

The NBA has continued to widen the lane, only hurting players who want to post up. At the start of the NBA, the lane was 6 feet wide. It was expanded to a width of 12 feet, and then now to 16 feet, all while its length remained constant. Previously, NBA players could set up near the basket and wait for their team to get them the ball, but players who do so now must wait at least 8 feet from the basket, and be faced with time pressure once they get any closer to the basket.

4.3: The Addition of the 3 Point Line

Perhaps the single most revolutionary development in the NBA was the addition of the 3-point line. The 3 point line changed offenses and defenses and it continues to do so, as teams continue to adapt to the new era. The more time that passes, the more three point attempts continue to rise, and the more pronounced the effects become on big men for both ends of the floor.

4.3.1: Effects of 3 Pointers on Offense

Before the NBA added a 3 point line, all baskets were worth two points. Because players shoot better from closer distances, it made sense that the closer a shot was to the basket, the greater expected value it had. This all changed with 3 pointers. Now, if a player was taking a shot from 20 feet away, they could take a step back, which while slightly lowering their overall percentage, would increase the expected points generated because the shot would be worth an extra point if it went in. The following diagrams demonstrate this phenomenon.

In general, shots from further away are converted at a lower percentage, with 3 pointers being the least likely to go in. However, teams don’t care just about the percentage; they care about the value. The 50% boost of value from 3 pointers leads to a very different diagram.

Looking at this diagram makes it seem that teams that were conscious of the statistics would want to only shoot 3 pointers and shots within 3 feet of the basket, minimizing everything in between. A look at the shot frequency throughout the league shows that teams have understood this and are going by the numbers.

It’s not surprising that the spots with the highest efficiency are the spots where teams take the most shots from. If a player wants to be good on offense (at least at scoring and attracting defensive attention), they either need to be able to effectively generate shots at the rim or be able to shoot 3 pointers. As already discussed with big men struggling to post up as efficiency keeps dropping, many get put in a situation where offensive production hinges on the ability to shoot 3’s. 10-15 foot jump shots just don’t cut it anymore, and big men who are subpar at posting up and long-range shooting have trouble getting very far in offensive systems. Big men were once considered to be spreading out if they could make mid-range shots, but the discouragement of these shots has led to noticeable declines in these shots each season, and the shots are being made up for with layups and 3 pointers.

4.3.2: 3 Pointers and Defense

Since 3 pointers have become more efficient and more utilized than every shot except for layups, many teams have started making sure that everyone on the floor can shoot, and offenses are now more spread out with usually 4 or 5 players staying behind the 3 point line, ready to catch and shoot or catch and attack while still keeping driving lanes open. While most big men with good strength are able to defend centers that only stay near the basket, they need to now be prepared for situations where all 5 opposing players are on the perimeter, at which point they will be forced to guard players on the perimeter. 

Centers can end up stuck on perimeter players even when the other team hasn’t put 5 shooters on the floor. This is due to the increased frequency of pick-and-rolls done between ball-handlers and big men, big men often have to be ready to switch onto ball-handlers, especially if the ball-handler can shoot if temporarily left unguarded. 

In this play, the Brooklyn Nets (black jerseys) run a pick and roll, and Bulls center Felicio (rightmost) will be forced to switch onto Nets point guard Russell (leftmost) and must be able to guard him. After successfully forcing a switch, if Felicio is a weak perimeter defender, then Russell can run an isolation play where the rest of his teammates spread out and leave him one-on-one with a slow, big man defending him. While screens are set almost every play (especially off ball), isolations aren’t used that often. However, there has been a trend of them increasing year by year, especially for the playoffs.

Teams are increasingly trying to take advantage of one-on-one possessions that arise from screens, and they do it even more in the playoffs when they have time to game-plan and figure out who the weakest defenders are and how to exploit them. If someone is unable to play one-on-one defense on the perimeter, teams will try to force that player into a situation where he is weakest. While it might be true that team basketball is generally more effective than individual basketball, the isolation possession NBA teams continue seeking are the specific ones that help add efficiency to their offense. Not only is the total amount increasing, but so is the profitability off of these situations.

There is a definitive trend that more isolation possession are leading to more points scored per each possession. Isolations are killing big men on defense, and the only reason that isolations even exist as a viable option is because of 3-pointers. Without 3-pointers, big men wouldn’t have any reason to come up to a perimeter player and risk getting blown by, as there would be no threat of leaving the player alone, far away from the basket. However, because any decent shooter must be guarded to at least the 3-point line, NBA teams are equipped with a weapon that can expose and diminish the value of anyone who isn’t quick and agile enough to guard perimeter players.

4.4: International Influence?

European basketball has often been known for placing higher emphasis on ball movement, shooting, and finesse, and their big have been playing for many decades in the manner that the NBA’s big men have adopted now. It is possible that the increased presence of foreign players has contributed to this transformation of big men, especially because foreign players are disproportionately centers and power forwards.

 

Section 5: The Future of NBA Big Men

The following are my opinions of what is most likely to happen to NBA big men given the current trends and assuming that there are no major rule changes in the near future:

• Big men who are unable to switch onto smaller perimeter players and guard them at an acceptable level will continue to be phased out of the league
• There will continue to be less posting up unless rule changes allow it to become more efficient
• Big men will continue shooting more 3’s
• Athleticism and agility will become even more important for most big men to be successful
• Big men who are unable to shoot from at least 15 feet when left wide open will continue to be phased out of the league
• Teams will put more value on big men who can switch on screens
• Gradual change will continue as young players grow up emulating modern big men instead of old school big men

 

Citations

• “67 Years of Height Evolution in the NBA – In-Depth Research.” Athletic Shoe Reviews, runrepeat.com/height-evolution-in-the-nba. 
• “Basketball Moves.” Wikipedia, Wikimedia Foundation, 11 June 2019, en.wikipedia.org/wiki/Basketball_moves. 
• Favale, Dan. “How Important Is the Pick-and-Roll in Today’s NBA?” Bleacher Report, Bleacher Report, 3 Oct. 2017, bleacherreport.com/articles/2199073-how-important-is-the-pick-and-roll-in-todays-nba. 
• Kirkgoldsberry. “How Mapping Shots In The NBA Changed It Forever.” FiveThirtyEight, FiveThirtyEight, 2 May 2019, fivethirtyeight.com/features/how-mapping-shots-in-the-nba-changed-it-forever/. 
• “NBA Rules History.” The Official Site of the NBA, http://www.nba.com/analysis/rules_history.html. 
• “Player Positions” HoopTactics, hooptactics.com/basketball-player-positions.
• “Switching & Iso Mismatches.” Dribble Handoff, dribblehandoff.com/stories/switching-iso-mismatches. 
• “Teams Post Ups.” NBA Stats, stats.nba.com/teams/tracking-post-ups/.