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Chemistry Experiments:
Part I -- Shot Blocking

We are pleased to announce the start of an ambitious multi-part series that will undertake to research and define the ideal characteristics of an NBA 5-man floor unit.


What would be the perfect 5-man unit?


You often hear reference to a team having good or bad 'chemistry' and while the implied tone has more to do with character/leadership and the like, we like to think of it in more real terms -- the group dynamics forged from the varying skills and qualities of the five players on the court a given time. To that end we will attempt in this "chemistry experiments" series to answer questions such as:

- what happens when you have no good passers on the floor?
- or, two or more excellent 'beat the defender off the dribble' players out there at the same time
- or, weak group offensive rebounding
- or you play a small lineup against the opposing team's big lineup...

...and a host of other ideas that come to mind.

5-Man Unit Shot Blocking Rating
We'll get the series rolling with an examination of the role of Shot Blocking in unit results. The first thing to decide is how we want to measure shot blocking ability, and while there are various metrics that could be proposed, we'll go with a simple one: percentage of shots blocked while on the floor.

So for example, Alonzo Mourning has had an incredible season in this regard, blocking 8.1% of the shots taken by the other team when he's on the floor (many of which of course he was nowhere near...his percentage of "blockable" shots is much, much higher). Like usual, if you go to the player in depth stats page, this number can be found (eg see Mourning's stats page), but here are some players to give you an idea of the range:

  • 8.1% - Mourning
  • 6.2% - Dalembert
  • 5.4% - Camby
  • 4.9% - Kirilenko
  • 3.8% - Brand
  • 2.7% - D.Howard
  • 2.1% - Garnett
  • 1.3% - McGrady
  • 0.6% - Bryant
  • 0.1% - Nash

So to calculate a given unit's block rating, we just add up the block % for each of the five players on the court at that moment. If you had a lineup of Nash-Bryant-McGrady-Garnett-Dalembert, you would score it as a 10.3 shotblocking unit (6.2 + 2.1 + 1.3 + 0.6 + 0.1). Or to use a more realistic example, the Golden State Warriors' two most used lineups are:

Davis-Richardson-Dunleavy-Murphy-Foyle -- good for a 6.4 unit block rating
Davis-Richardson-Dunleavy-Diogu-Murphy -- with a 4.0 unit block rating

We elected to use six groupings of units:

- 0 to 3.9 shotblocking 'points'
- 4 to 4.9
- 5 to 5.9
- 6 to 6.9
- 7 to 7.9
- 8+ shotblocking points

This represents a reasonably even distribution of the total units played in the NBA this season, but obviously any unit with Mourning out there is automatically in the "heavy shot blocking" range regardless of the other four players!

NBA 2005-06 Season to 2/14
("Garbage time" excluded)
Points per 100 Possessions
Defensive Stats
Unit Block Rtg
Offense
Defense
NET
FG%
Blk%
Close
Shot
Quick
Shot
FTA/
FGA
Off.
Reb%
T/O
 0 to 3.9 109.6  108.1  +1.5  .450  5.2  33.8%  38.4%  .30  28.4%  14.9% 
 4 to 4.9 106.4  108.0  -1.6  .453  5.2  34.5%  36.9%  .30  28.9%  15.6% 
 5 to 5.9 106.3  106.3  +0.0  .448  5.6  33.7%  37.2%  .29  29.4%  16.1% 
 6 to 6.9 106.5  106.2  +0.3  .451  5.9  34.0%  36.9%  .27  30.6%  16.6% 
 7 to 7.9 106.0  106.2  -0.2  .450  6.5  34.8%  35.8%  .26  30.0%  15.7% 
 8+ rtg 105.0  105.5  -0.5  .447  7.8  35.4%  36.9%  .28  31.4%  16.5% 

Looking at the above table, we can start to understand the effect of having a certain level of shot blocking among your players in a 5-man unit. As might be expected, the defense gets better the stronger your shot blocking prescence is -- gauged by the "defensive points per 100 possesions allowed, where it goes from a 108.1 rating for a unit with the lowest level of shot blocking down to 105.5 for a team with the highest shot blocking rating.

Of course, this isn't football -- you don't have separate offensive and defensive units! You've got to play both ways in the NBA, and in what may be a surprise, the best performing unit characterisitc in terms of net points per 100 possessions was the unit with the least shot blocking ability! We need to be careful in jumping to conclusions though, as there is lots of complexity to this beyond the simple isolation on shot blocking we are looking at.

Some definite trends emerge:
- units with good shot block ratings allow fewer free throws
- units with good shot block ratings force more turnovers
- ...but units with good shot block ratings also allow opponents to collect more offensive rebounds
- units in the highest class of shot blocking show a noticeable decline in offensive efficiency

Also important to note is that shot blocking is to some extent a function of role, which is demonstrated in the table -- for the low rated units, the block % is higher than the unit rating, suggesting when there's a void a player will step up to fill the "interior defender" role when he might usually not be the last line of defense guy. Likewise the super high block rated units "underperform" since they may have two guys usually accustomed to being the primary blocker now sharing the job.

Given this last point, another look is to see only what the highest individual block rating is for a unit...

Highest Shot Block% player of the unit
So this time we'll group the units by the rating of the best shot blocker of the five, rather than the combined score of all the unit. This time we'll narrow it to five groupings:

- 0 to 1.4 shotblocking 'points'
- 1.5 to 2.4
- 2.5 to 3.4
- 3.5 to 4.4
- 4.5+

Points per 100 Possessions
Defensive Stats
Highest Block Rtg
Player
Offense
Defense
NET
FG%
Blk%
Close
Shot
Quick
Shot
FTA/
FGA
Off.
Reb%
T/O
 0 to 1.4 110.7  109.6  +1.1  .455  4.6  33.6%  40.2%  .32  27.1%  14.0% 
 1.5 to 2.4 107.4  106.7  +0.7  .450  5.4  34.2%  36.6%  .29  29.5%  16.3% 
 2.5 to 3.4 106.3  106.7  -0.4  .448  5.6  33.9%  36.8%  .28  30.5%  16.2% 
 3.5 to 4.4 105.5  106.4  -0.9  .451  6.3  33.8%  36.2%  .27  29.2%  15.3% 
 4.5+ rtg 105.3  105.8  -0.5  .447  8.0  36.4%  37.8%  .28  31.3%  16.5% 

There are only 16 players with 4.5 or better block ratings, well 15 now that NOK's Andersen has been banned. Of these several are strictly part time players, but given we are filtering out garbage time that diminishes the chance for someone like Darko Milicic to screw things up! (Darko has a horrible -94 plus/minus at a -32 per 48 minutes rate!)

The results are to say the least a tad surprising -- having a strong shot blocker in the five man unit is not on a league wide basis a plus -- the units running without a big shot swatter have actually got the positive net points per possession, whereas the big shot blockers are in the red! The defense does get better with the increase in shot blocking ability, but at a serious cost in offensive efficiency.

Are teams putting too much emphasis on having the shot blocker? Can you win going small? Hmmm. Perhaps it has something to do with the style of defense -- relying less on the big men stepping in on drives and more on a team effort to contest shots, and pull down those defensive rebounds. In part it's because a number of the players with giant shot blocking ratings have horrible "non garbage time" plus/minus: Josh Smith -199, Przybilla -147, and Ostertag -113 for starters.

That doesn't account however for the 2.5 to 4.4 leading block rating in a unit also showing negative net points per possession. For fans who appreciate high scoring games, this could be good news: optimizing the offense instead of the conventional wisdom of optimizing defense, may be a decent strategy.

A next step could be to do a cross-matchup of the units on the floor.

Unit versus Unit Shot Blocking Matchup
Using the original six groups for total unit shot blocking (adding up the ratings for all five players on the floor), and the "highest block rating of the five" you get the following:

Combined Block Ratings of all five players
Points per 100 Possessions
Unit Block Rtg
Opp. Unit Rtg
Offense
Defense
NET
 0 to 3.9  4 to 4.9 110.0  108.4  +1.6 
 0 to 3.9  5 to 5.9 107.9  107.6  +0.3 
 0 to 3.9  6 to 6.9 108.8  105.2  +3.6 
 0 to 3.9  7 to 7.9 111.6  105.4  +6.2 
 0 to 3.9  8+ rtg 106.5  105.7  +0.8 
 4 to 4.9  0 to 3.9 108.4  110.0  -1.6 
 4 to 4.9  5 to 5.9 106.2  107.2  -1.0 
 4 to 4.9  6 to 6.9 108.1  107.9  +0.2 
 4 to 4.9  7 to 7.9 106.8  105.8  +1.0 
 4 to 4.9  8+ rtg 106.0  108.1  -2.1 
 5 to 5.9  0 to 3.9 107.6  107.9  -0.3 
 5 to 5.9  4 to 4.9 107.2  106.2  +1.0 
 5 to 5.9  6 to 6.9 106.8  108.2  -1.4 
 5 to 5.9  7 to 7.9 105.2  105.3  -0.1 
 5 to 5.9  8+ rtg 105.7  105.2  +0.5 
 6 to 6.9  0 to 3.9 105.2  108.8  -3.6 
 6 to 6.9  4 to 4.9 107.9  108.1  -0.2 
 6 to 6.9  5 to 5.9 108.2  106.8  +1.4 
 6 to 6.9  7 to 7.9 108.1  110.4  -2.3 
 6 to 6.9  8+ rtg 103.8  102.0  +1.8 
 7 to 7.9  0 to 3.9 105.4  111.6  -6.2 
 7 to 7.9  4 to 4.9 105.8  106.8  -1.0 
 7 to 7.9  5 to 5.9 105.3  105.2  +0.1 
 7 to 7.9  6 to 6.9 110.4  108.1  +2.3 
 7 to 7.9  8+ rtg 104.6  104.6  +0.0 
 8+ rtg  0 to 3.9 105.7  106.5  -0.8 
 8+ rtg  4 to 4.9 108.1  106.0  +2.1 
 8+ rtg  5 to 5.9 105.2  105.7  -0.5 
 8+ rtg  6 to 6.9 102.0  103.8  -1.8 
 8+ rtg  7 to 7.9 104.6  104.6  +0.0 
Highest Player Rating of the Five on court
Points per 100 Possessions
Highest Player Block Rtg
Highest Opp. Player Rtg
Offense
Defense
NET
 0 to 1.4  1.5 to 2.4 111.1  110.7  +0.4 
 0 to 1.4  2.5 to 3.4 109.9  105.0  +4.9 
 0 to 1.4  3.5 to 4.4 110.1  109.0  +1.1 
 0 to 1.4  4.5+ rtg 108.7  107.1  +1.6 
 1.5 to 2.4  0 to 1.4 110.7  111.1  -0.4 
 1.5 to 2.4  2.5 to 3.4 106.2  106.6  -0.4 
 1.5 to 2.4  3.5 to 4.4 105.1  106.0  -0.9 
 1.5 to 2.4  4.5+ rtg 106.5  103.8  +2.7 
 2.5 to 3.4  0 to 1.4 105.0  109.9  -4.9 
 2.5 to 3.4  1.5 to 2.4 106.6  106.2  +0.4 
 2.5 to 3.4  3.5 to 4.4 108.6  104.0  +4.6 
 2.5 to 3.4  4.5+ rtg 105.3  107.8  -2.5 
 3.5 to 4.4  0 to 1.4 109.0  110.1  -1.1 
 3.5 to 4.4  1.5 to 2.4 106.0  105.1  +0.9 
 3.5 to 4.4  2.5 to 3.4 104.0  108.6  -4.6 
 3.5 to 4.4  4.5+ rtg 104.8  104.6  +0.2 
 4.5+ rtg  0 to 1.4 107.1  108.7  -1.6 
 4.5+ rtg  1.5 to 2.4 103.8  106.5  -2.7 
 4.5+ rtg  2.5 to 3.4 107.8  105.3  +2.5 
 4.5+ rtg  3.5 to 4.4 104.6  104.8  -0.2 

In both cases the successful nets points per possession units are the ones with the lowest block ratings!

Go Figure.

Now you might begin to think from all of the above that shot blocking is over-rated: it helps the defense but "hurts" the offense. Putting out an "offensive liability big man" seems like a mistake if you're not in an end game state of subbing out offense for defense. We would remind you though that the differences are small, and may well be explainable by other causes.

Indeed, you could glean a similar surface level read on blocks just by doing basic team correlations, or heck by the recent Do Player Awards foretell a team's success? article for SI.com in which we pointed out that the team with the league leading shot blocker had won on average only 42 games a season, with zero titles in the 23 years we examined, and only 39% of the time made it to the second round of the playoffs.

The next extension of this analysis is to look at things on a team by team basis (how the mighty Pistons' starting five have fared against different shot block levels, or in a "Kobe stopper" type mindset where you focus on a high scoring opponent). That however is the type of thing we save for the less publicly accessible parts of the site...

So let notice be served that this was just the warm-up exercise. When we come back from our All Star break we'll be laying down some serious research on this mysterious and elusive notion of the ideal 5-man unit!


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