NBA Combines, Box Agility Test, and Defensive Performance

Last weekend, I attended the Boston Sports Medicine and Performance Group Conference. The conference is one of the best conferences in the country for strength and conditioning coaches and sports medicine professionals, and regularly draws some of the best speakers. At the conference, former Oakland A’s and current N.C. State strength and conditioning coach Bob Alejo was one of the speakers. 

He mentioned that he hired Brett Brungardt, the guy who runs the NBA pre-draft combine, to come to Raleigh and test his players. He showed the Box Agility Test (also called the Laneline Agility Test) on video, and said that NBA scouts had told him that they can determine who can be a good defensive player based on the first two steps of the test. I disagreed with the comment, and the tests in general, so I dug into the numbers.

To get an idea, I looked up the Box-Agility Test scores for the players who made 1st or 2nd Team All-Defense this season in the Draft Express database. The database had agility scores for 5 of the 10 players:

  • Tony Allen (2004) – 10.70 seconds
  • Chris Paul (2005) – 11.09 s
  • Michael Conley Jr. (2007) – 11.63 s
  • Joakim Noah (2007) – 11.79 s
  • Tyson Chandler (2001) – 12.13 s

 

To offer perspective, the top 3 scores in the database are:

  • Mustapha Farrakhan (2011) – 8.18 s
  • Isaiah Thomas (2011) – 8.22 s
  • Andrew Gouldelock (2011) – 8.23 s

 

Also, the two best scores for players over 6’8 in bare feet in the database are: Ralph Sampson (2011) – 9.12 s and Josh Harrellson (2011) – 9.20 s.

To offer more perspective, here are players with the same or similar times who are not all-defensive performers:

  • Tony Allen (10.70): Chuck Hayes 10.70, Shawne Williams 10.69
  • Chris Paul (11.09): Ronald Dupree 11.09, Michael Beasley 11.06
  • Michael Conley Jr. (11.63): Trevor Ariza 11.63, Nick Collison 11.62
  • Joakim Noah (11.79): Terrence Ross 11.78, Lonny Baxter 11.77
  • Tyson Chandler ( 12.13): Monta Ellis 12.13, Mark Madsen 12.12

 

As evidenced by some of the examples, some aspect of being a great defensive player is not measured in the Box Agility Test.

There are two primary problems with the Box Agility test: (1) It may not be an agility (CODS) test, and (2) There is no coupling of perception and action.

There is no published reliability and validity information for the Box Agility Test that I have found. An unpublished thesis (Brown, 2012) found the test to be reliable. However, to establish validity for the test, Brown (2012) compared the test to the T-Test. The T-Test has been shown to be a measure of speed, not agility (Pauole, Madole, Garhammer, Lacourse, and Rozenek, 2000), so the positive relationship between the Box-Agility Test and T-Test did not provide validity for the Box-Agility Test being a test of agility.

Agility as a construct lacks of a precise definition (Jeffreys, 2011; Holmberg, 2009; Sheppard & Young, 2006). More recently, agility has been divided into two categories: reactive agility (or agility) and planned or pre-planned agility, also referred to as change of direction speed (Safaric & Bird, 2011; Young & Wiley, 2009; Oliver & Meyers, 2009). Planned agility involves a closed skill where movements are known ahead of time (Oliver & Meyers, 2009). Reactive agility is an open skill that captures the perceptual and decision-making skills required within a game context (Jeffreys, 2011; Serpell, Young, & Ford, 2011). Most tests of agility traditionally have used pre-planned movements and applied the test results to open-skill sports (Cooke et al., 2011; Pound, 2007). This is the case with the Box-Agility Test. It is a pre-planned test.

If defense was merely a physical skill, this would not be problematic. However, as we know, basketball involves much more than physical quickness. The best defensive players anticipate. Has Shane Battier (2001 – 10.95 s) been a great defensive player because of his foot speed or his perceptual skills? The perceptual abilities thought to differentiate expert and non-expert players include pattern recognition and the ability to predict and anticipate an opponent’s behavior (Aglioti, Cesari, Romani, & Urgesi, 2008). These abilities are untested in a pre-planned test like the Box-Agility Test, and ultimately these are the abilities that most differentiate the expert defenders.

Whereas the NBA combine uses a pre-planned test (and another test that uses a response to lights) that shows virtually no ability to discriminate elite and sub-elite defensive players, reactive agility tests have discriminated elite and sub-elite players in netball (Farrow, Young, & Bruce, 2005), Australian Rules Football (Young & Wiley, 2009), and rugby (Gabbett & Benton, 2009). These tests use a live person or a video screen in the testing, as opposed to a planned course of cones.

The Box-Agility Test is one small data point for NBA General Managers to evaluate before making a selection. However, to suggest that it reveals who will and will not become a great defensive player in the NBA is false. Basketball defense goes beyond the physical – every change of direction is made as a reaction to an external stimulus. These directional changes and movements are never pre-planned. It is the coupling of these perceptual abilities with the physical qualities that makes one a great defender.

As a side note, potential lottery pick Dennis Schroeder had the exact same test score in the Box-Agility Test as Chris Paul. 

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