Thunder's leaky 'D' threatens chances at winning it all

When the Oklahoma City Thunder out-gunned the Golden State Warriors 119-116 on Tuesday, it was the fifth time this season that OKC had won a game in which it allowed at least 100 points. That's a lot in a season during which teams are averaging less than 95 points a game.

The Thunder are slightly better than average defensively, ranking 15th by allowing 99.9 points per 100 possessions entering Thursday's game in Sacramento (10:30 p.m. ET, TNT). Offensively, they rank third, scoring 105.6. They're a great team, with a four-game lead in the loss column on the rest of the Western Conference, but they're unbalanced. And if they want to win a championship, they'll probably need to improve defensively.

When the Thunder won 55 games and made the conference finals last season, it was mostly seen as a progression from the season before, when they won 50 games and lost in the first round. But though the rosters were virtually identical (91 percent of last season's minutes were played by guys who were on the roster the season before), those two teams were very different.

The 2009-10 Thunder were a top-10 defensive team. The 2010-11 Thunder were a top-five offensive team. Only four teams improved more offensively from '09-10 to '10-11, and only three teams regressed more defensively.

There were a few of things that contributed to the identity change. First, Russell Westbrook and James Harden both became more potent scorers. Second, the Thunder lost assistant coach Ron Adams, who kept their young players focused on defense, to the Chicago Bulls. And of course, as they improved offensively, there was less pressure to defend as well as they did in '09-10.

Last February, though, the Thunder made a defensive upgrade when they acquired Kendrick Perkins from the Celtics. They allowed less than a point per possession in Perkins' 428 minutes last season, and were the eighth-best defensive team after the All-Star break.

So with a full season of Perkins and Serge Ibaka as their starting bigs, OKC should have been an improved defensive team, back in the top 10. But they've actually regressed defensively when you compare their numbers to the league average (which has dropped considerably from last season).

When Thabo Sefolosha was healthy, the Thunder starters were excellent defensively but really struggled on the other end of the floor. With James Harden at the two instead of Sefolosha, they're ridiculously good offensively, but terrible defensively. And with Daequan Cook starting, they've been pretty bad on both ends.

Of 182 players who have logged at least 500 minutes this season, Harden has the highest offensive efficiency (his team's points per 100 possessions when he's on the floor) at 112.8. But he also has the second-highest on-court defensive efficiency among players on teams with winning records, at 104.6 and behind only Mo Williams.

• NBA.com/stats: Thunder efficiency with Harden on and off the floor.

Harden's offense has more than made up for his defense, but it's an interesting yin-and-yang situation the Thunder have with Harden and Sefolosha, who have played only 72 minutes together this season.

Overall, the Thunder defend both 2-point and 3-point shots pretty well, ranking fifth in opponent effective field-goal percentage. But they don't rebound well, don't force many turnovers and foul too much. The turnovers are the biggest difference between this Thunder defense and the one from two seasons ago, when they forced 15.7 per 100 possessions, the sixth-highest rate in the league.

But the biggest defensive difference when Harden is on the floor this season is free throws. Thunder opponents are attempting 33 free throws per 100 field-goal attempts with Harden on the floor, but just 20 with him on the bench.

Serge Ibaka's minutes have been split evenly between time spent with Harden on the floor and time spent with Harden on the bench. And they make it clear that Harden's perimeter defense puts added pressure on the Thunder bigs protecting the basket.

In 296 minutes with Harden on the floor, Ibaka is averaging 4.3 fouls per 36 minutes. In 380 minutes with Harden on the bench, Ibaka is averaging just 2.8 fouls per 36 minutes.

The Thunder obviously aren't getting rid of Harden. The question is whether they can win a championship as an unbalanced offensive team.

This is a unique season. Every team out there is just trying to survive the condensed schedule. But in the last 20 seasons, only eight teams that didn't rank in the top 10 defensively in the regular season have made The Finals. And only two of those, the 2000-01 Lakers and the 1994-95 Rockets, have won a championship.

The Thunder will either need to buck that trend or buckle down on defense.

John Schuhmann is a staff writer for NBA.com. You can e-mail him here and follow him on twitter.

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