When the Boston Celtics assembled their Big Three in the summer of 2007, a 35-year-old Shaquille and Zydrunas Ilgauskas were the second-leading scorers on Dwyane Wade and LeBron James’ teams respectively. Five years later, Boston’s run was ended in Game 7 of the Eastern Conference Finals by a Big Three of the Miami Heat they influentially helped create.

The NBA was a much different place the year before Kevin Garnett and Ray Allen joined Paul Pierce. The San Antonio Spurs were rarely challenged en route to their third championship in five years, steamrolling a 51-win Utah Jazz team and a 50-win Cleveland Cavaliers team while going 8-1 in the final two rounds of the playoffs.

With three All-NBA caliber players in their prime, San Antonio had dominated the NBA, winning three titles and finishing inches short in 2004 (Derek Fisher’s 0.4 shot) and 2006 (Dirk Nowitzki’s and-1 in Game 7). The Phoenix Suns, who never played enough defense, were the only team with comparable talent, as most of the league’s top players were on one-man squads.

Garnett, Pierce and Allen were no exception; all three missed the 2007 playoffs. None had ever played with a true equal, and they had combined to make only three career Conference Finals appearances: Allen in 2001, Pierce in 2002 and Garnett in 2004.

In Boston, they formed a trio better than the sum of its parts. Garnett, one of the most athletic and skilled 7’0 of all-time, anchored the defense, while his passing ability was the perfect offensive complement to two knock-down shooters. On the perimeter, Pierce and Allen had complementary games, despite both being 6’5+ wings with career averages of 20+ points on 45% shooting. Even though he lacked elite athleticism, Pierce was an dominant isolation scorer. Allen, one of the best three-point shooters in NBA history, didn’t need to play with the ball in his hands.

Just as importantly, Celtics general manager Danny Ainge held on to Rajon Rondo and Kendrick Perkins as he built his team. Rondo, an elite athlete and passer at the point guard position, got his Hall of Fame teammates open shots while they spaced the floor for him. Perkins had the bulk to defend the low-post, which gave Garnett the freedom to roam the floor defensively and cause havoc.

Blowing away the conventional wisdom that teams needed time to gel before they won a title, the Celtics went 66-16 in the regular season and 16-10 in the playoffs to win the 2008 championship. Ainge dramatically raised the bar the previous summer; the rest of the NBA has spent the last five seasons catching up.

The Lakers responded first, acquiring Pau Gasol, an All-NBA seven-footer, when they still had Kobe Bryant, Lamar Odom and Andrew Bynum. But the Lakers, one of the longest and most skilled teams in NBA history, still came up short against Boston in the 2008 NBA Finals. In their second season together, Boston raced out to a 43-12 record before Garnett suffered a serious knee injury. Los Angeles took advantage to win the 2009 NBA Finals, but they still needed more talent if they were going to overcome a healthy Celtics team.

That summer they acquired a fifth All-Star caliber player in Ron Artest, a 6’7, 260 former Defensive Player of the Year. The 2010 Finals were a dramatic rematch of 2008, with Artest’s defense on Pierce and Perkins’ untimely injury in Game 6 proving the difference. The amount of talent was mind-boggling: the Lakers countered Boston’s five former or future All-Stars (Rasheed Wallace and what had become the Big Four) with three of their own, a future Sixth Man of the Year (Odom) and a PG with five rings (Fisher).

The two teams, primarily made up of players drafted from 1996-2001, won five of six conference titles from 2008-2010. It was a wake-up call to the top players from the 2002-2005 drafts, who were on comparatively punchless squads that repeatedly came up short. In the 2010 playoffs, Wade averaged 33/6/7 on 54% shooting and lost to Boston in 5; LeBron averaged 29/9/8 on 50% shooting and lost in six.

Wade, LeBron and Bosh received a lot of criticism for their unprecedented decision to team up in the summer of 2010, but one of the driving forces behind “The Decision” was a Celtics team with an almost unprecedented amount of talent. Rondo, after making the last three All-Star and All-Defensive teams, has a chance to be a Hall of Famer, which would make Boston the first team since the 1980’s with four future Hall of Famers playing major roles.

In an alternate universe where the Big Three ended their careers in relative anonymity on fringe playoff teams, the last four years of NBA history would have to be completely rewritten. Now, after barely surviving a lockout, the league is poised to enter the dawn of what could be a spectacular era of basketball.

In 2007, LeBron James played on the NBA’s biggest stage with four starters who had combined for two All-Star appearance in their careers. To get by Boston in 2011 and 2012 and return to the Finals, he needed a supporting cast with 15. “The Decision” may end up changing the NBA and the 2010’s could end up rivaling the 1980’s, but none of it would have happened without the Celtics.