By the end of the 120-112 beating they gave the Thunder in Game 2 of the Western Conference Finals, the San Antonio Spurs looked like the best team in the NBA. While most of the league struggled with injuries and inconsistency following the lockout, San Antonio rolled to their 13th consecutive 50-win regular season despite playing in only 66 games. They took it to another level in the playoffs, ruthlessly dispatching the Jazz and the Clippers before getting out to a 2-0 lead over the Thunder. Oklahoma City had gone 8-1 through the first two rounds, but they seemed to have no answer for the free-flowing ball movement of the Spurs offense, ranked No. 1 in the league.

Then, in a little over a week, it was over. Instead of winning their fifth title in the Tim Duncan era, they were wiped out of the playoffs in the next four games. In Game 4 of the WCF, the Thunder scored 109 points and shot 54% from the field. In Game 5, 108 points on 50% shooting. In Game 6, 107 points on 50% shooting. San Antonio was only a few stops from reaching the NBA Finals and they could not get them. They have continued winning regular-season games with metronome-like consistency in 2013, but they are a different and much better team this season. The Spurs are playing defense again.

The Spurs' defensive collapse last year shouldn’t have come as a surprise. Despite their reputation as a defensive juggernaut, they had quietly remade themselves into a finesse, offensive-minded team. With Robert Horry long gone and Tim Duncan aging, they no longer had the long and athletic big men necessary to field an elite defense. After consistently finishing in the top-3 for most of the last decade, their defense had slipped to No. 10 by 2012. As a result, defeating the Thunder was always going to be an uphill battle. By Game 6 of the WCF, with Boris Diaw starting and only Stephen Jackson and Gary Neal getting minutes off the bench, the Spurs had abandoned any hope of stopping Oklahoma City.

The Spurs' frontcourt is much younger and more athletic this season. Tiago Splitter has emerged as a second 7’0 to play next to Tim Duncan while Kawhi Leonard has taken the sophomore leap and become an excellent two-way SF. As a result, their defense has skyrocketed back into the top-3. Neither Splitter nor Leonard can anchor a defense by himself, but playing them in tandem greatly increases the Spurs team speed and athleticism. Their starting five (Parker-Green-Leonard-Splitter-Duncan) has an eye-popping net defensive rating of 84 points allowed per 100 possessions. Both Splitter and Leonard rate highly on an individual level as well, with nearly identical defensive ratings of 95.8 and 95.6 respectively.

Splitter, a 28-year old center from Brazil, came to the NBA in 2010 after a distinguished career in Europe. An athletic 6’11 240 big man with a 7’2 wingspan, he has above-average quickness for a player his size as well as a good feel for the game. He was expected to be a high-level contributor immediately, but he’s needed two seasons to adjust to the speed of the NBA as well as the demands of the Spurs system. Previously, his minutes were capped because Gregg Popovich did not think he could play with Duncan, given that neither is an elite outside shooter. This season, as Duncan and Splitter have become more comfortable together, they’ve developed the ability to play off of each other, allowing San Antonio to maintain their floor spacing without needing to give heavy minutes to defensive liabilities like Matt Bonner and Diaw.

Leonard, an athletic 6’7 225 combo forward with a 7’2 wingspan, is the most athletic perimeter defender the Spurs have had since Bruce Bowen. A 21-year old from San Diego State, he’s taken a dramatic leap forward in his second season, particularly on the defensive end. His defensive rating has gone from 102 as a rookie to 95.8 this year, an impressive jump which indicates his mind is starting to catch up with his body. Combine that with the ability to space the floor and a high overall skill level and he’s the rare young frontcourt player capable of contributing on both sides of the ball. Most importantly, his combination of size, speed and length gives San Antonio someone who can physically match up with elite combo forwards.

The Big Three and Popovich get most of the headlines for San Antonio, but the play of Splitter and Leonard will ultimately determine their season. The Spurs offense has been a championship-level unit for years; their lack of speed and athleticism upfront has been their Achilles heel since 2007. They had no answer for Pau Gasol and Lamar Odom in 2008, Dirk Nowitzki in 2009, Amar’e Stoudemire in 2010, Zach Randolph in 2011 and Durant in 2012. This season, all roads to a championship go through Oklahoma City and Miami, who are built around the two best players in the NBA, uber-athletic 6’9+ combo forwards capable of playing inside and out and almost uniquely designed to punish weak front-court defenses.

In playing Splitter and Duncan together, the Spurs have bucked the recent trend in the NBA. Floor spacing has become the name of the game, to the point where the Lakers benched Gasol in order to play Earl Clark. The Heat don’t have a single 7’0 who receives playing time, while the Thunder have been most effective when they bench Kendrick Perkins and play Serge Ibaka at the 5. Both Miami and Oklahoma City benefit from going small because it increases the amount of space for Durant and LeBron James to operate, but that’s not an issue for San Antonio, as the machine-like execution of their offense allows them to thrive despite playing two big men who can’t shoot 3’s.

The $64,000 question for the Spurs is whether Splitter’s presence on the floor can dictate matchups in a close playoff game. Last season, when Scott Brooks played Durant at the 4, Popovich blinked first, taking his second big man out of the game and going small with Leonard and Jackson upfront. He might be able to con Brooks into keeping Perkins on the floor by sticking with Splitter, but Erik Spoelstra will almost certainly force Splitter to defend Shane Battier 25+ feet from the basket if San Antonio makes the NBA Finals. That type of matchup swung the 2012 Finals, as Perkins could not punish the Heat when they had Battier guarding him in the low post while Oklahoma City’s conventional lineup could not defend the spread-out Miami attack.

Splitter is much more skilled than Perkins, but he’s hardly a primary offensive option either. However, if his off-ball cuts in the paint and offensive rebounding can force Spoelstra to keep Chris Anderson or Udonis Haslem on the floor, Miami suddenly becomes mortal. In the 2012 WCF, the Spurs tried to beat the Thunder at their own game, with predictably disastrous results. This season, San Antonio has returned to their roots, sacrificing a bit of their offensive efficiency in order to play more defensively-sound lineups that feature two conventional big men. It may not be enough to get them a fifth championship, but it at least gives them a fighting chance, something they haven’t really had in the last few years.