Reports are that the NBA is changing the All-Star ballot to compensate for the relative dearth of centers in the NBA. They are taking the "center" position off the ballot and now, fans will just vote for three frontcourt slots. David Aldridge of NBA.com explains, 

The league will announce Wednesday a change to its All-Star ballot that will, for the first time, allow fans to vote for three undefined "frontcourt" players instead of having to vote for two forwards and a center. With more and more teams playing smaller than in the past, the definition of "center" was becoming increasingly difficult -- not to mention finding enough quality big men for whom to vote.

For the first 50 years of NBA history, the center was the most important position in basketball. Now it's become so obsolete it doesn't even merit its own spot on the ballot. So what happened? 

Michael Jordan happened. 

Jordan electrified the league, bringing unprecedented attention to the NBA. TV ratings exploded. For example, the four highest rated NBA Finals of all-time featured Jordan's Bulls. The highest rated of all-time came in 1998 with a rating of 18.7. 

With Jordan retiring the NBA was concerned for the health of the game. How were they going to market the league? The hunt was on for the next Michael Jordan, and player after player fell short of the task. 

Harold Minor, Vince Carter and Kobe Bryant were all dubbed the "air apparent" at one time or another. However, even Bryant couldn't touch Jordan's level of success with the existing rules being what they were. 

What Rules Were Changed and Why They Were Changed

So the NBA started implementing rule changes to make it easier for players who weren't Jordan to emulate the same things he did. Even the zone defenses, often cited as something that works against perimeter players, had the impact of making it easier.

There is a misconception that there was a single rule or single year where the rules were changed. Actually, it was a series of rule changes which spanned seven years from the 1997-1998 season to the 2004-2005 season. 

In 1998, the hand check rule was changed to say, "A defender will not be permitted to use his forearm to impede the progress of an offensive player who is facing the basket in the frontcourt."

In 2000  two more changes were implemented. First, there was a clarification on the hand-check rule, 

 In the backcourt, there is no contact with hands and forearms by defenders. In the frontcourt, there is no contact with hands and forearms by defenders except below the free throw line extended in which case the defender may only use his forearm. In the post, neither the offensive player nor the defender is allowed to dislodge or displace a player who has legally obtained a position. Defender may not use his forearm, shoulder, hip or hand to reroute or hold-up an offensive player going from point A to point B or one who is attempting to come around a legal screen set by another offensive player. Slowing or impeding the progress of the screener by grabbing, clutching, holding “chucking” or “wrapping up” is prohibited.

And, 

 Any defense is legal on the strong side. Defenders must remain on the weak side outside the paint unless they are double-teaming the ball, picking up a free cutter or closely guarding an offensive player.

In 2001, there was more clarification:

No contact with either hands or forearms by defenders except in the frontcourt below the free throw line extended in which case the defender may use his forearm only.

In 2002, 

 Illegal defense guidelines will be eliminated in their entirety.

A new defensive three-second rule will prohibit a defensive player from remaining in the lane for more than three consecutive seconds without closely guarding an offensive player.

There is a misconception that zone defenses balance out the removal of the hand-checking rules. That's not true because of the institution of defensive three seconds. Because of that, big men could no longer hang out in the paint. That opens up the paint for driving wings. 

The intended effect happened, and the game moved away from the big man. 

Finally, in 2004-05, the rules were, "introduced to curtail hand-checking, clarify blocking fouls and call defensive three seconds to open up the game.

The last five words of that last clarification is crucial, "to open up the game." There is no question that the intention of the rule changes was to open up the game because the people that made the rule changes said why they were doing it, and they said that it was to open up the game. 

The Proof it Worked

Prior to Jordan, the game had been dominated by big men for virtually its entire history. The league's first MVP was awarded in 1956. From that time until Larry Bird won in 1983, the award had gone to a center all but two times. The only exceptions were Bob Cousy and Oscar Robertson. 

Larry Bird won the next three, then the Michael Jordan era began. Over the course of the Jordan era, there were six winners that weren't Jordan. Karl Malone won twice, Magic Johnson, Charles Barkley, David Robinson and Hakeem Olajuown each won once. 

Since Jordan retired (if you don't count the Wizards years), only one center, Shaquille O'Neal, has won, and he won during the early part of the rule changes which opened up the game. 

Since 2005, no centers have won. It's the longest span of time in NBA history where a center didn't win the award. Six of the seven winners were players who generated their teams offense through ball handling. 

The traditional center is gone. 

Even the "forward-center" doesn't really qualify. For example, Tim Duncan is often called a center, even if the Spurs don't call him one. Setting aside the question of what you then call the player filling the center spot on San Antonio, the argument is moot.

Even if Duncan is a center, he's not the traditional center; he's a modern center. The modern center has changed to adapt to the rules the way they are now. Centers no longer score their points at the rim. They score from further out.  

When Duncan won the MVP in 2002, 56.2 percent of his points came more than three feet away from the rim. 

When he won in 2003, over 61.0 percent of his field goals came away from the rim.

Yao Ming, at the peak of his career, was a center whose scoring came more than three feet away from the basket. According to basketball-reference, he shot 61.0  percent of his shots from at least three feet out in 2006-07.

Shaquille O'Neal, by contrast, had only 40 percent of his field goals come outside of three feet in 2001. 

The point here is that for centers, the game is moving away from the basket. It's not just a few isolated cases, either, and it has an impact of the overall scoring. Since 2005, only two centers, Shaquille O'Neal and Dwight Howard, have scored more than 20 points per game for a season with more than half his points coming within three feet of the rim. 

No center has averaged more than 23 points and had more than half their shots within three feet. Four centers have only accounted for 20 point per game seasons on just 10 occasions regardless of where the scoring has come from. 

In the seven years prior to when the rule changes started taking place, there were 36 centers who scored 20 points, and virtually all of them were players who scored the bulk of their points at the rim, although the shot details aren't available. 

Yao Ming's 25.0 points, which is the highest average since the rule changes, would only be tied for 14th in the seven years from 1991-1998.

Yes, there is a slower game now, with an average of five possessions fewer per game in 2012 than there were in 1992. Even if you account for pace, though, it only accounts for 0.8 points, not the dramatic difference here. 

Nor does it explain why scoring for wings has gone up. Using the same parameters, there were 127 20-point scorers who were pure forwards or guards from 1991-98 compared to 165 over the last seven years. Granted, there are a few players on both of those lists who are power forwards, but not enough to skew the difference. 

Some will say "numbers don't mean everything." Of course, I'm not arguing they do here. I'm arguing that the numbers show that the rules had the intended effect, not that they "mean" anything. The numbers don't lend meaning to the argument; they defend it. 

It is a point of fact. Scoring has shifted from the center to the wings since the implementation of rules that were intended to have that impact. 

The numbers do make that indisputable. 

Post Hoc Ergo Procter Hoc Or Occman's Razor?

One of two things is true here. Either it's just a coincidence that the changes that the rules were designed to affect happened after the rule changes or it's caused by it. 

Some could argue that it's "post hoc ergo propter hoc" or "after this, therefore because of this." If I drop my pencil and at that exact moment my light bulb burns out, that doesn't mean that dropping my pencil caused the light bulb to burn out. 

Just because there was a dearth of big men after the rule changes doesn't mean that the rule changes caused the drop off in productive big men. 

That's where it's important to understand where the center shots are coming from and why it matters that Tim Duncan is attempting his shots from away from the rim. He's shooting from there for a reason. 

It used to be that behind every great center, there was a great guard to spread the court for him with his shooting and/or passing. There was Kareem Abdul-Jabbar and Magic Johnson, John Stockton and Karl Malone, Willis Reed and Walt Frazier. The center to score at the rim and the guard to feed him the ball and score from outside. 

Now, the roles are a bit reversed. Centers and bigs are stepping away from the rim to draw their defensive counterparts with them away from the rim. Duncan is opening up the lane for Tony Parker, Carlos Boozer is opening up things for Derrick Rose and Chris Bosh is opening the way for LeBron James and Dwyane Wade. 

Occman’s Razor argues that when there are competing hypotheses, the explanation that requires the fewest assumptions is the best. That the rules changed the game in the way it intended to change it (i.e. opening up the game) by causing the very thing they wanted to (move the centers away from the rim), which would result in their objective (create more Jordans) leaves no room for assumption.

Perhaps the single best argument for Jordan as the greatest player of all-time is this: No other player had such an impact on the game that the NBA changed the rules to duplicate him. When Wilt Chamberlain dominated, they changed the rules to curtail his dominance. When Jordan dominated, they changed the rules to replicate his dominance. The side effect, though, was that there will never be another Chamberlain.