Change from Illegal defense to "Zone" had little to no impact

[LKN]

I keep seeing claims on here that the introduction of "zone" defense (in quotes since the NBA does not allow real zones) had a huge impact on the game. Yet It's hard to find evidence that there was a big impact on league offense. Conversely, the removal of hand-checking in 2004-2005 had a massive impact on league ORTG that is obvious and easy to see.

The truth is that the defensive era of the early 00s started well before the removal of illegal defense rules - this is clear in the data:

League ORTGs:

1996 - 107.6
1997 - 106.7
1998 - 105.0
1999 - 102.2
2000 - 104.1
2001 - 103.0
2002 - 104.5 <= "Zone" defense allowed
2003 - 103.6
2004 - 102.9
2005 - 106.1 <= Hand-checking removed
2006 - 106.2
2007 - 106.5
2008 - 107.5
2009 - 108.3
2010 - 107.6


Starting in 1996, the league ORTG steadily decreased every single year until 1999. 1998 was the first time league ORTG dropped below 106 in about 15 years (1983 was the last sub-106 year prior to 1998).

ORTG then stabilized between 102 and 104 until 2004. The change to remove illegal defense in 2001-2002 actually resulted in a large jump in ORTG which then dropped the next two years until it was the same as it way in the last year prior to the rule change.

In 2005 we saw the removal of hand-checking which caused a massive jump in ORTG. It was the first year since 1997 where ORTG was above 106. ORTG then steadily increased for a few years until stabilizing back at 1981-1997 levels until the removal of rip through fouls in 2011-2012 (there was a huge drop in ORTG that year).


mademan makes a good point - It appears that:

"Zone" w/o handchecking produces almost identical ORTGs to "illegal defense" w/ handchecking.


The question remains why ORTG fell so much from 1998-2004 (and why it started falling in 1996).


Interesting, there were small changes to illegal defense almost every year starting in 1998:

https://cdn.nba.net/nba-drupal-prod/nba-rules-changes-history.pdf


Could explain some of this... but it's really hard to tease out the data because the NBA changed the rules almost every year in that period (which is nuts). I really wish we had data (maybe someone does) on how often illegal defense was called. Like if there was a big drop each year maybe I'd buy these yearly changes making an impact

[mademan]

By those numbers, handchecking didn’t really have an effect either

[LKN]

By those numbers, handchecking didn’t really have an effect either

The 2005 rule change pretty clearly had a huge impact.

But you make a fair point - ORTG (other than a big dip in the early 00s and a small dip that started in 2011-2012) has basically been the same forever (well until the last 2 years).

I guess the bigger question is why did the league ORTG start falling in 1996 and why was it so low from 1998 to 2004.

It's fair to say that "Zone" + no handchecking has produced very similar results to "illegal defense" + handchecking.

[mademan]

By those numbers, handchecking didn’t really have an effect either

The 2005 rule change pretty clearly had a HUGE impact.

But you make a fair point - ORTG (other than a big dip in the early 00s and a small dip that started in 2011-2012) has basically been the same forever (well until the last 2 years).

I guess the bigger question is why did the league ORTG start falling in 1996 and why was it so low from 1998 to 2004.

It's fair to say that "Zone" + no handchecking has produced very similar results to "illegal defense" + handchecking.

You could come to the conclusion that rule changes over the past 30 years have had no effect and the drop or rise in ortg for a period is due to the talent in the league. Early 2000s and late 90s was a big drop off in talent in the league.

[LKN]

By those numbers, handchecking didn’t really have an effect either

The 2005 rule change pretty clearly had a HUGE impact.

But you make a fair point - ORTG (other than a big dip in the early 00s and a small dip that started in 2011-2012) has basically been the same forever (well until the last 2 years).

I guess the bigger question is why did the league ORTG start falling in 1996 and why was it so low from 1998 to 2004.

It's fair to say that "Zone" + no handchecking has produced very similar results to "illegal defense" + handchecking.

You could come to the conclusion that rule changes over the past 30 years have had no effect and the drop or rise in ortg for a period is due to the talent in the league. Early 2000s and late 90s was a big drop off in talent in the league.

Was there a drop of in talent from 2012 through 2015 (another smaller dip in ORTG occurred then)?

That also would imply talent was constant from 1983 through 1996 or 1997

I'm not sure that's a great argument - but I won't dismiss it out of hand.

[nikster]

By those numbers, handchecking didn’t really have an effect either

The 2005 rule change pretty clearly had a HUGE impact.

But you make a fair point - ORTG (other than a big dip in the early 00s and a small dip that started in 2011-2012) has basically been the same forever (well until the last 2 years).

I guess the bigger question is why did the league ORTG start falling in 1996 and why was it so low from 1998 to 2004.

It's fair to say that "Zone" + no handchecking has produced very similar results to "illegal defense" + handchecking.

You could come to the conclusion that rule changes over the past 30 years have had no effect and the drop or rise in ortg for a period is due to the talent in the league. Early 2000s and late 90s was a big drop off in talent in the league.

I think its also that these changes require significant time for coaches to adjust their gameplans too. If you give coaches the experiences of running a zone defense the last 20 years condensed into the off season, we might see a larger drop in ORTG when the change occurs

[HypeMode]

Kobe Bryant stated that the illegal defense rule was to stop stars. While star players had a hit in their production, role players made up for it by hitting 3s in the open holes of the zone.

[LKN]

The 2005 rule change pretty clearly had a HUGE impact.

But you make a fair point - ORTG (other than a big dip in the early 00s and a small dip that started in 2011-2012) has basically been the same forever (well until the last 2 years).

I guess the bigger question is why did the league ORTG start falling in 1996 and why was it so low from 1998 to 2004.

It's fair to say that "Zone" + no handchecking has produced very similar results to "illegal defense" + handchecking.

You could come to the conclusion that rule changes over the past 30 years have had no effect and the drop or rise in ortg for a period is due to the talent in the league. Early 2000s and late 90s was a big drop off in talent in the league.

I think its also that these changes require significant time for coaches to adjust their gameplans too. If you give coaches the experiences of running a zone defense the last 20 years condensed into the off season, we might see a larger drop in ORTG when the change occurs

Fair point - the 3 point revolution certainly took a REALLY long time.

Really though - before the last two years the league ORTG has basically been constant forever other than 1998-2004 and 2012-2015 (the change between 1998-2004 was MUCH larger than 2012-2015 which was more of a minor dip).

[dhsilv2]

Zone had a lot of impact, but it's a lot more subtle than this. The whole spread the floor with 3 point shooters while in part driven by the rockets/curry was also a counter to the thibb's flooding system. Zone makes it much easier to for example defend a post player, it got to the point where only Kobe who'd spent a decade mastering the game could still really manage it from the high post. That was a direct result of zone. But that doesn't mean offenses can't do something else.

The point is it is hard to tie league offensive rating to defensive rule changes.

The other issue is that the NBA is a copy cat league and frankly offenses change faster than defenses. So yes rules have changed the game. Yes rules have changed offensive rating. But trying to tie a change in defensive rules to a change in offensive rating is going to be harder and more tricky than a change for offense.

[Wallace_Wallace]

So back then, do you think it's easier to score or it's easier to defend ?

[LKN]

Zone had a lot of impact, but it's a lot more subtle than this. The whole spread the floor with 3 point shooters while in part driven by the rockets/curry was also a counter to the thibb's flooding system. Zone makes it much easier to for example defend a post player, it got to the point where only Kobe who'd spent a decade mastering the game could still really manage it from the high post. That was a direct result of zone. But that doesn't mean offenses can't do something else.

The point is it is hard to tie league offensive rating to defensive rule changes.

The other issue is that the NBA is a copy cat league and frankly offenses change faster than defenses. So yes rules have changed the game. Yes rules have changed offensive rating. But trying to tie a change in defensive rules to a change in offensive rating is going to be harder and more tricky than a change for offense.

Counterpoint - the impact of the 2005 rule change is totally obvious (and not just in league ORTG data - it's totally obvious in individual stats too).

(not dismissing what you are saying; Just pointing out an instance where it was easy to tie changes to ORTG to a rule change)

You bring up some interesting points - good post.

[LKN]

So back then, do you think it's easier to score or it's easier to defend ?

Neither actually, outside of 1998-2004 it's been roughly the same since the early 80s until the last couple of years. (there was a brief dip from 2012-2015 also, but it was much less drastic than 1998-2004).

That's team wise of course.... we'd have to dig deeper to see how individual player stats have changed (and whether it's easier/harder for different types of players).

[dhsilv2]

Zone had a lot of impact, but it's a lot more subtle than this. The whole spread the floor with 3 point shooters while in part driven by the rockets/curry was also a counter to the thibb's flooding system. Zone makes it much easier to for example defend a post player, it got to the point where only Kobe who'd spent a decade mastering the game could still really manage it from the high post. That was a direct result of zone. But that doesn't mean offenses can't do something else.

The point is it is hard to tie league offensive rating to defensive rule changes.

The other issue is that the NBA is a copy cat league and frankly offenses change faster than defenses. So yes rules have changed the game. Yes rules have changed offensive rating. But trying to tie a change in defensive rules to a change in offensive rating is going to be harder and more tricky than a change for offense.

Counterpoint - the impact of the 2005 rule change is totally obvious (and not just in league ORTG data - it's totally obvious in individual stats too).

(not dismissing what you are saying; Just pointing out an instance where it was easy to tie changes to ORTG to a rule change)

You bring up some interesting points - good post.

I think I said one thing a bit wrong.

There's defensive strategy rule changes, like illegal defense and then there's procedural or I dunno what is a foul if you will. A rule that is designed around strategy is different from one designed around the flow of basketball. Even things that aren't rule changes but refs call differently can fall into this.

Zone requires coaches to come up with strategies and they then have to counter the counter from the offense. This is complex and takes time to implement. Even say the restricted area, it took more time for defenses to adapt to where to position themselves than it took for the offense to just keep doing what they already did and now they have less risk of an offensive foul.

If refs stop calling moving screens, it's a hell of a lot easier to get a shooter open without any changes to the game. Just like if you don't hand check...well the guy was already going to drive, now it's just easier.

[Wallace_Wallace]

So back then, do you think it's easier to score or it's easier to defend ?

Neither actually, outside of 1998-2004 it's been roughly the same since the early 80s until the last couple of years. (there was a brief dip from 2012-2015 also, but it was much less drastic than 1998-2004).

That's team wise of course.... we'd have to dig deeper to see how individual player stats have changed (and whether it's easier/harder for different types of players).

I believe there are rules that favor the offense (IE handchecking removal), and players that still excel under the new rules on defense should be recognized. Guys like Paul George, Andre Iguodala, Kawhi Leonard, Chris Paul, Tony Allen, Draymond Green, etc. they still get put down compare to the players in the 90's. That's one of the disingenuous point I see a lot. If fans can say Michael Jordan would average an absurd amount of points in today's game, then same fans should be able to admit that those defenders would be hell to score on without the rules. We never hear that. It's completely fair to say Kawhi Leonard is on par with MJ defensively, if not better. Even that, some thinks it's absurd.

[Antinomy]

So LKN, I’m guessing what you’re really trying to say is that the rules don’t affect anything.

[LKN]

So back then, do you think it's easier to score or it's easier to defend ?

Neither actually, outside of 1998-2004 it's been roughly the same since the early 80s until the last couple of years. (there was a brief dip from 2012-2015 also, but it was much less drastic than 1998-2004).

That's team wise of course.... we'd have to dig deeper to see how individual player stats have changed (and whether it's easier/harder for different types of players).

I believe there are rules that favor the offense (IE handchecking removal), and players that still excel under the new rules on defense should be recognized. Guys like Paul George, Andre Iguodala, Kawhi Leonard, Chris Paul, Tony Allen, Draymond Green, etc. they still get put down compare to the players in the 90's. That's one of the disingenuous point I see a lot. If fans can say Michael Jordan would average an absurd amount of points in today's game, then same fans should be able to admit that those defenders would be hell to score on without the rules. We never hear that. It's completely fair to say Kawhi Leonard is on par with MJ defensively, if not better. Even that, some thinks it's absurd.

To be clear - I'm not one of those people. I don't like it when people run down past great players, but running down current guys who are actually great is also terrible.

We should be enjoying all these players.

I would agree that guys like Kawhi and Lebron would be pretty scary if they were allowed to manhandle guys.

[draftnightsuit]

Zone had a massive impact. It killed isoball and post play and forced teams to hit their 3s.

[LKN]

So LKN, I’m guessing what you’re really trying to say is that the rules don’t affect anything.

Actually what I'm doing is looking at data and attempting to form hypotheses.

Like some things are very obvious (2005 rule changes, current freedom of movement changes). It's hard to see any obvious impact of the removal of illegal defense.

Some rule changes do have large impacts - others don't... others (like the 3 point line) take a long time to have their full impact.

One problem here is the NBA changed several rules (some repeatedly) really quickly starting in 1998 (which was honestly dumb) so it can be difficult to tease out exact results.

I'm still not totally sure why league ORTG had dropped so much prior to illegal defense being removed

[LKN]

Some had a massive impact. It killed isoball and post play and forced teams to hit their 3s.

Actually 3PAs didn't really change that much between 1995 (when we had 15.3 per game) and 2012 (when we had 18.4 per game).

After that it's been going up steadily every year (although some of that is also due to the increasing pace since then).

[draftnightsuit]

Some had a massive impact. It killed isoball and post play and forced teams to hit their 3s.

Actually 3PAs didn't really change that much between 1995 (when we had 15.3 per game) and 2012 (when we had 18.4 per game).

After that it's been going up steadily every year (although some of that is also due to the increasing pace since then).

I didn’t say it forced them to take more 3s, I said it forced them to make their 3s.

3P% increased every season starting in 2003 and peaked at 36.7% in 2009. That is the highest % in NBA history (along with ‘96 in the shortened 3-point line era). But 2009 is the best 3-point shooting year with the real 3-point line.

Since then, it’s leveled off between 35-36% every year. In recent years, the volume has been increasing while the efficiency remains the same.

Under illegal defense rules, teams could spread the floor and artificially create space because double-teaming was illegal. The implementation of zone means that teams have to hit their 3s to create space. That’s why claiming that it’s easier to score today is ridiculous.