Get To Know An Advanced Stat: Individual defense

In the first installment of the 'Get To Know An Advanced Stat' series, I explained why defensive rating (and offensive rating) was the best measure of overall team defense as compared to raw points allowed or opponents field goal percentage, but what about individual defensive measures?

As with most sports, defense is the hardest part of basketball to quantify. You can't properly evaluate how well a player defends based solely on numbers (A player can play great defense and give up two points on a circus shot, then play lazy defense on the next possession and have his opponent brick a wide open jumper or layup). To get a good feel for how a player defends, you must watch him play defense, both on the ball and off.

Having said that, however, if you are looking for numbers and metrics to aid in your evaluation of individual defense, as with most stats nowadays, there is more at your disposal today than ever before.

In addition to rebounding (which I already went over here), the most basic individual defensive stats have always been blocks and steals, but like other stats in today's efficiency based basketball world, we now have the option to look at blocks and steals in 'rate' or 'percentage' form as opposed to simply looking at per game or per minute numbers.

For example, steal percentage measures the percentage of opponent possessions while a player is on the floor that end with that player recording a steal. So while DaJuan Blair is tied for 16th with 1.7 steals per game, his steal percentage of 4.0 actually ranks fourth (Tony Allen's steal percentage of 4.6 leads the league).

Block percentage is the percentage of opponents' two-point field goal attempts while a player was on the floor that the player in question blocked. Just as they do in basic blocks per game, Anthony Davis and Roy Hibbert lead the league in block percentage as well, blocking 9.2 and 8.2 percent of their opponents' two-point attempts while on the floor, respectively.

One important thing to keep in mind when it comes to blocks, however, is that while blocking a shot to prevent the opposition from scoring is great, it's less valuable if you're simply swatting the ball into the stands and helping the opposing team retain possession (and remember that a possession doesn't end until possession of the ball switches hands, regardless of how many shots a team gets). For this reason, one of the more underrated and valuable defensive stats available to us is the percentage of a player's blocked shots that his team actually rebounds. Looking at the elite defensive Pacers as an example: just 50 percent of David West's 20 blocks this season have been rebounded by the team, while an incredible 72.6 percent of Hibbert's 62 blocks have resulted in an Indiana rebound and a possession change.

Another important factor to monitor when looking at players' defensive numbers is their foul rate and more specifically, their foul rate compared to the number of defensive plays they make. Recording blocks and steals is fine and dandy, but if a player can't get it done without committing a lot of fouls and putting the opposing team on the free throw line, it's not very beneficial to their team's overall defense. A good example is 'The Big Fundamental' himself, as Tim Duncan ranks eighth in the NBA with 1.9 blocks per game and eighth with a block percentage of 4.9, but leads the NBA with 1.3 blocks per foul. John Wall leads the league with 1.3 steals per foul, meanwhile. TeamRankings.com also has a handy stat that combines all defensive plays recorded per foul, where Jimmy Butler leads with 2.56 defensive plays per infraction (albeit in a smaller sample size, as Butler has only played in nine games).

Keep in mind as well that blocks and steals can also be indications of players gambling on defense and not always playing within their team's defensive principles. Though at the same time, while the decision to go for a steal or a block may not always be the smart one, once the actual block or steal is recorded (and retained), it becomes a worthwhile defensive play.

As with most evaluation measures, player tracking data has also enhanced our options when it comes to individual defense. Through Synergy Sports' website, you can break down Paul George's individual defense by situation. For example, George has allowed just 0.52 points per possession in 23 opportunities to defend in isolation situations this season, 0.68 points per possession when guarding the ball handler in 71 pick-and-roll situations and 0.93 points per possession in 75 opportunities to defend spot-ups. Over at NBA.com, we can see that Brook Lopez, rarely given credit for his rim protection, holds opponents to an incredible mark of just 33.7 percent shooting in 8.9 attempts at the rim per game, far and away the best mark in the league among players who defend any considerable number of attempts at the rim.

Another option, of course, is individual defensive rating. Just as team defensive rating measures how many points per 100 possessions a team allows, the individual form of this 'advanced' stat is an estimate of how many points per 100 possessions a player allows when defending. Not surprisingly, Roy Hibbert leads the league in defensive rating with a mark of 90.1, but for evidence that this measure still lends favor to players on good defensive teams, consider that four of the top-five, six of the top-nine and seven of the top-15 individual defensive ratings right now belong to Pacers. Having said that, it's no wonder that of the 10 Pacers who have logged at least 100 minutes so far this season, none affect the team's defensive rating quite like Hibbert, as that rating goes from a team-best 87.8 with Hibbert on the floor to 95.7 with the Defensive Player of the Year candidate on the bench (Although not a perfect solution, a good habit to get into when you feel a player's numbers may be influenced by the team around him is to check the on-court/off-court measures now available to us).

Quantifying defense is as tricky a statistical basketball task as any other, and your best hope of being able to evaluate this paramount facet of the game is still by watching as much ball and as much of a specific player as you can (in addition to keeping up to date with the numbers). But again, we're living in a golden age of basketball statistics, especially when it comes to the NBA, so if you're looking for worthwhile options when it comes to advanced individual defensive measures, there's no shortage out there.

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Read more in the Get To Know An Advanced Stat series.
On Offensive/Defensive Rating: http://beta.thescore.com/nba/news/341984
On Effective Field Goal Percentage & True Shooting Percentage: http://beta.thescore.com/nba/news/350333
On Rebound Rate: http://beta.thescore.com/nba/news/356883
On Assists and Passing: http://beta.thescore.com/nba/news/364440