The 15-year chain reaction that led to the NBA's current offensive explosion

Even as Mike D'Antoni was about to change the NBA forever, he wasn't sure he was doing the right thing.

In the weeks leading up to the start of the 2004-05 season, D'Antoni, then entering his first full season as head coach of the Phoenix Suns, was planning on doing something the NBA hadn't seen before. With recently signed point guard Steve Nash at the controls, D'Antoni was hoping to play a brand of small ball that was decidedly against conventional wisdom. By moving 6-foot-7 wing Shawn Marion to power forward and 6-foot-10 power forward Amar'e Stoudemire to center, D'Antoni was hoping to space the floor with shooters around Stoudemire's deadly ability in the pick and roll and run opponents off the court with superior speed and quickness.

But even though D'Antoni, who became a legendary player in Italy, believed this was the way to play, he was having trouble convincing himself he could make such a massive break from basketball convention until he had a conversation with Jerry and Bryan Colangelo, the father-son duo then running the Suns.

"When I talked to Bryan and Jerry and said, 'God, you know, I'm a little stuck because I want to go this way, but I don't know. It's not traditional,' " D'Antoni said in a recent phone interview. "And they go, 'Mike, do what you think's best and don't worry about anything. Do what you think is right.' . . . They gave the final nod to try it, because I had no idea."

It turned out D'Antoni had the perfect idea. In today's NBA, playing small with multiple shooters spread across the half court isn't just a feasible way to play; it's the preferred way to build a team. More than a decade later, then, the ripple effects from D'Antoni's decision to introduce to the NBA a new way to play are still being felt, as the league heads into the second half of the 2016-17 regular season with a level of offensive production unseen in decades.

Russell Westbrook is on pace to become the first player since Oscar Robertson, in 1962, to average a triple-double for a season. On the heels of Stephen Curry becoming the first player to surpass not only 300 three-pointers in a season but 400, finishing with 402 last year, the league is firing triples at an unprecedented rate. Lumbering 7-foot centers jack them up like players a foot shorter. Virtually every team is trying to play smaller and faster and get up more perimeter shots, eschewing the traditional path of playing through dominant centers and relying on defense. Even Sunday's All-Star Game in New Orleans followed the trend, as a free-flowing series of dunks and threes allowed the West to emerge with a 192-182 victory and Anthony Davis to earn MVP honors with a record-setting 52 points.

The league has arrived at this moment because of a 15-year evolution focused around three key aspects, all of which have taken the sport from the rough-and-tumble fisticuffs that defined the 1990s to the free-flowing game of today: space, speed and smarts.

While D'Antoni's Phoenix teams get much of the credit for reshaping the way the sport is played, the beginnings of today's offensive explosion can be traced back to something that had happened a couple of years earlier: the elimination of the illegal-defense rule in 2001.

The decade leading up to the rule change had become defined by isolation basketball. Superstars such as Michael Jordan and Allen Iverson had perfected the art of isolating a defender on one side of the court and then scoring in bunches while their teammates stood around and watched.

But while some looked at eliminating the illegal-defense rule as a way to promote ball movement and open up the game, others - such as Miami Heat Coach Pat Riley, who had perfected the way to play under those rules with the Heat and New York Knicks in the 1990s - felt that changing the rules to allow for zone defenses would actually slow the game down further.

"Before, I mean, people would just stand out above the top of the key and isolate somebody on the wing or on the low post, and the only thing you could do was come double-team or stay where you were," Detroit Pistons Coach Stan Van Gundy, then working as an assistant under Riley, said recently. "You couldn't get down in the lane or things like that, and so at first I know the thinking of all of us was, 'That should really give an edge to the defense.' "

Instead, Van Gundy said, it did something else: It forced coaches to begin to think differently about offense.

"What it sparked was we can't play offense the same way," Van Gundy said. "That isolation game is not going to work now."

But while the illegal-defense change helped, an equally important shift was removing defenders' ability to hand-check before that 2004-05 season. This change promoted freedom of movement for the individual players, just as the illegal-defense change promoted more ball movement.

Anyone who sees footage of one of the games between those Knicks and Heat teams in the 1990s will immediately notice how physical defenders are, riding offensive players all the way down the court.

"If you remember, it was hard to watch the NBA at that time," Golden State Warriors Coach Steve Kerr said. "Games were 90-85, and defenses were beating each other up and beating the offenses up. I think the league really made some good changes with the illegal-defense rule and allowing you to zone and kind of encouraging pace and flow."

The new landscape proved fertile for fresh ideas, primed for someone to take advantage of the new rules. In stepped D'Antoni and his Suns.

To say people were skeptical of D'Antoni's tempo-pushing plans is an understatement.

"Everybody was telling me it wouldn't work," D'Antoni said. "They were telling me all year. The biggest thing I was hearing was that I was going to destroy their careers, that I was going to hurt them. 'They can't play that way, they won't last 'til December, they won't last 'til February, they won't last 'til March.'

"But we just kept going, and it worked and it worked."

The 2004-05 Suns weren't supposed to become the NBA's next powerhouse. When Nash signed a six-year, $63 million contract with Phoenix that summer, the deal was seen as a huge risk. The Suns had won just 29 games the year before, and D'Antoni had gone 21-40 after taking over early in that season.

By playing small, though, and with Nash at the controls, the Suns suddenly were blazing a trail that left everyone else struggling to keep up - both in terms of pace of play, as D'Antoni's famed "Seven Seconds or Less" offense had Phoenix playing faster than everyone else - and wins. Phoenix began the year 31-4 and went on to tie a franchise record with 62 wins, reaching the Western Conference finals for the first of two straight seasons. Nash also won the first of two consecutive most valuable player awards.

For D'Antoni, getting off to the fast start was essential, since it proved that the plan could work. Struggling out of the gate might have forced him to pivot.

"If we had started off slow, I don't know if I had enough gumption to hang in there or knew enough to get over the hump," D'Antoni said. "It's easier now because it's kind of accepted, but back then you were kind of flying without a map.

"But we started off 31-4. It was fun. ... We were killing people. I do remember one day when I walked into Bryan's office in the morning, and we always met and talked about 8 o'clock in the morning, and I think at that point we were 31-4 or whatever, and we looked at each other and started laughing and said, 'Can you believe this?' and we kind of chuckled. That's how the whole setting was. It was like, 'Wow.' "

It was a reaction the rest of the league shared. While D'Antoni's teams didn't wind up winning a championship during his four-year run in Phoenix - thanks in part to a series of unlucky breaks along the way - it didn't take long for others to embrace his vision.

Van Gundy took over the Orlando Magic in the summer of 2007 and inherited a team with a franchise centerpiece in Dwight Howard, the game's dominant big man at the time. Howard was a pick-and-roll monster offensively and the league's best defensive player by a significant margin. It was the perfect setting to employ a variation on D'Antoni's scheme.

In 2009, Orlando reached the NBA Finals playing a similar style, spacing four perimeter players around Howard. Rashard Lewis, a small forward, most notably played as the team's power forward.

Like D'Antoni before him, Van Gundy wasn't confident in the plan. He wasn't planning to utilize it at all, in fact, until projected starting power forward Tony Battie suffered a shoulder injury in September.

"It's exactly what they said about necessity being the mother of invention," Van Gundy said. "It was essentially, 'We're going to get our best players on the floor.' . . . It was simply we didn't have a better option at the time and we had one of the best pick-and-roll big guys, if not the best, in the league . . . so it just sort of all came together."

The success of Phoenix and Orlando began to affect the league's collective psyche. Teams saw that those teams weren't simply exceptions to the norm but, in the process, had discovered the best way to play the game under the new rules. Soon multiple teams, and star players, were following suit.

LeBron James and Chris Bosh - career small and power forwards, respectively - moved to power forward and center when their Miami Heat teams were at their best. Draymond Green's ascension into the starting lineup in Golden State, triggered by an injury to incumbent starter David Lee, was a catalyst that helped convert the Warriors from a good team into the league's best.

During this time, use of data began to creep more and more into the basketball world, further allowing teams to tailor strategies in more effective ways, in a manner easily digestible for coaches and players.

The biggest impact has come in shot distribution. Players and coaches from previous eras lament the "loss" of the midrange shot - jumpers 10 to 20 feet from the basket - from today's game, saying it's a fundamental art that has been lost to layups or three-pointers. The data, however, shows that those midrange shots are the least efficient shots in basketball; shooting fewer directly correlates to improved offensive output.

That was something D'Antoni brought to the league in Phoenix and that the data confirmed. Now, as the coach of the Houston Rockets, he has unleashed a barrage of threes and turned James Harden into an MVP candidate in the role Nash had played a decade earlier.

"When I was in Phoenix and we shot in the 30s [in terms of three-pointers attempted] and you're being criticized for shooting too many threes, then I would back off a little bit," D'Antoni said. "[I'd say], 'You may be right' and maybe ease off and throw some post-ups in there or have people coming around and shooting midrange jump shots. I would go there because I didn't have any data.

"Once the data came out and said, 'Even more threes are better' or 'Open it up even more and get space and get to the hoop,' it gave me more courage as a coach and more cocksuredness to do what I wanted to do. [But I] was afraid to take it all the way, I guess."

The combination of all of these factors led to the NBA's offensive explosion this season. The spacing created by just about every team spending at least significant portions of games playing with at least four players who can shoot three-pointers has led to an increase in three-point attempts that has climbed nearly every season.

Pace of play has gradually increased since that 2004-05 season, to the point where the movement is now creating far more possessions in each game - in turn leading to the proliferation of triple-doubles by stars such as Westbrook and Harden.

The increase in data, and the quest for efficiency, has given teams a road map that coaches could only guess at 15 years earlier when the league made that pivotal decision to eliminate illegal-defense calls.

"I've always said that I think what we see today is a culmination of when they changed the rules in 2001," Portland Coach Terry Stotts said. "They wanted to bring freedom of movement and skill and opening up the court and moving it from the side of the court to the middle of the court.

"I think gradually that's how the game changed and became what it is today, because of those rule changes. That was radical at the time, and there's no question the game is better because of it."

After those changes, D'Antoni's Suns showed everyone how to exploit them. Even though the innovations didn't deliver championships to D'Antoni personally, they did pave the way for others.

When Heat Coach Erik Spoelstra won his first championship as a head coach, in 2012, he texted D'Antoni and thanked him. And when Kerr and former Suns assistant Alvin Gentry won a championship with the Warriors in 2015, they, too, credited D'Antoni for starting the NBA down the path it is now on.

"I was just excited," D'Antoni said of the appreciation from other coaches. "Excited for them, excited that the way we wanted to play wasn't totally off. I think that's the biggest thing . . . that I'm not crazy and I'm not completely wrong."