The Value Of A Blocked Shot | NBA Playbook

The Value Of A Blocked Shot

I am here at MIT Sloan Sports Analytics Conference, and looking through the number of great papers one of them caught my eye.  It was called “The Value of a Blocked Shot in the NBA: From Dwight Howard to Tim Duncan” written by John Huizinga, (A professor of business at the University of Chicago) who has been Yao Ming’s NBPA registered agent since Yao’s inaugural season, representing Yao in his dealings with the Houston Rockets, as well as with major endorsement partners.

Data

Before getting into the data and what it tells us, it was important for us to learn how the data was gained.  Mr. Huizinga developed a database called Chances.  The database uses data provided by STATS, LLC. and allowed everyone to know the context of the action before the block.  The sample of the data used in the presentation was players with over 100 blocks over the last 7 years (this is when the data has become available).  In total, this ended up being 170 player-seasons.

Type Of Block

Is blocking a lay-up more valuable than blocking a jump-shot?  Mr. Huizinga’s data says yes.  In his presentation, he said that it all comes down to expected value.  A jumper has an expected point value of 1.04 while a lay-up has an expected point value of 1.54.  Looking at it this way, Brendon Haywood, who many people is a very good defender (me included) actually is a less valuable shot blocker than Jermaine O’Neal.

Haywood gets 69% of his blocks on jumpers, meaning he only blocks 31% of the more valuable lay-ups.  On the other end of the spectrum, 91% of Jermaine O’Neal’s blocks were on lay-up attempts, while only 9% of his blocks were the less-valuable jump shots.

“Russells”

Many people who have seen Bill Russell play (or have seen highlights) know that Bill Russell was remembered for blocking shots for his teammates, starting a fast break (called by Bill Simmons as “Russells”.  Mr. Huizinga showed that this doesn’t really happen in the NBA anymore.  There have only been 7 players (in the 7 season where the data was tracked) who accumulated more than 20 “Russells” in a season.

Preblock Situation

One of the most important things to take away from Mr. Huizinga’s presentation is expected value of the preblock situation.  Or in otherwords, what happened right before the block took place.  Naturally, a block coming off of a live-turnover situation on a lay-up (think a LeBron chasedown) is going to be more valuable than a block coming off of a deadball situation.  Again, this comes down to expected point value.  The expected point value of a live-turnover situation is higher than a deadball situation because coming off of a live-ball turnover, the defense doesn’t have a chance to get back.

The best shot blocker in the NBA when it comes down to this situation ends up being Andrei Kirilenko, as 16% of his blocks come against this shot type.  The worst ends up being Greg Ostertag.  This makes sense considering that Ostertag isn’t really known for his footspeed.

Putting It All Together

So whose blocked shots are the most valuable?  Mr. Huizinga closed the presentation by going over what he calls “Block Value.”  To determine block value, he used the formula Points Saved + Points Created where Points Saved equals the effect of a Block on Opponents Expected Points during this possession and Points Created equals the effect of a Block on Own Team’s Expected Points During the next possession.

Using this formula, we found out who had the best season since the data started being collected (2002-03) in terms of overall block value.  It ended up being Theo Ratliff during his 2003 season.  Ratliff accumulated a block value of 300 (287 coming from points prevented while 13 came from points created), which when transformed into wins ends up being right around 5.

Interesting Numbers

Just thought it would be interesting to include some numbers towards the end of Mr. Huizinga’s presentation, showing how number of blocks can’t really be used when determining who is the best “shot blocker.”

2003 season

  • Stromile Swift | 119 blocks with a block value of 74
  • Rasho Nesterovic | 117 blocks with a block value of 124

So why was Mr. Huizinga’s paper called From “…Dwight Howard to Tim Duncan?”  Well as he explained, through a series of charts, Tim Duncan has had the best season in history when it came down to value/block with 1.12, meaning he saved 1.12 points with every block and Dwight Howard ended up with the worst season in terms of value/block with with .53 (both came during the 2008 season).

Stats, LLC
06
Mar 2010
POSTED BY admin
POSTED IN Analysis Defense TrueHoop at MIT Sloan Sports
DISCUSSION 11 Comments
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  • brennan

    his analysis may be acceptable comparing one shot blocker to another, but when analyzing how many points or wins the shot blocker is worth he is missing a HUGE part of the value of a shot blocker.

    Pretty much any basketball player or coach will tell you that while a shot blocker may only block a few shots a game (to have 10 in a game is a spectacular performance), often what’s even more important is the fear he instills in the opponents when they attempt a shot near the hoop. It usually leads to shots taken at a tougher angle, or with more arc, that ultimately are going to be less successful, on average.

    Unfortunately this impact would be very hard to accurately quantify. You could perhaps compare a player or teams average success of a given shot (especially near the basket) against the success of a given shot with the shot blocker on the court. There may not be enough data to do this, and unfortunately this still doesn’t accurate gauge the plays when the shot blocker truely affected the shot (if a layup was taken and he was 15 feet away, he most likely had little to no impact on the shooter’s decision making (note he still could have some small impact, because players do take more notice of who is around them when taking a shot when a known shotblocker is on the floor. Even if he ends up being farther away, being “in the shooter’s head” can affect shots)).

    This may also affect the analysis of comparing a shot blocker to another shot blocker, since the overall impact against the opposition that a shot blocker has could vary and be very significant.

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  • Ignarus

    Value per Block is probably going to be excessively harsh on Howard – keep in mind that he still gets a LOT of blocks! He’s also intimidating in the paint and athletic enough to threaten the layups and dunks of guys like Lebron James (moving their offense out of the paint) while a more efficient shot-blocker simply may not have the athleticism to challenge those shots.

    Still, I love the analysis and really only mean to point out the intimidation value of the beefy, 12th-row, dunk-swat to guys who care about highlights. Yeah, it’s technically less valuable if it doesn’t change how ppl on the floor think and play, but seemingly, intimidation DOES work, just like guys will get out of the way to avoid being posterized by a mega-dunker on defense.

    Still, it’s awesome to see yet another statistical way to point out how fantastic Tim Duncan is, because he just doesn’t get the credit he deserves.

  • Ignarus

    Value per Block is probably going to be excessively harsh on Howard – keep in mind that he still gets a LOT of blocks! He's also intimidating in the paint and athletic enough to threaten the layups and dunks of guys like Lebron James (moving their offense out of the paint) while a more efficient shot-blocker simply may not have the athleticism to challenge those shots.

    Still, I love the analysis and really only mean to point out the intimidation value of the beefy, 12th-row, dunk-swat to guys who care about highlights. Yeah, it's technically less valuable if it doesn't change how ppl on the floor think and play, but seemingly, intimidation DOES work, just like guys will get out of the way to avoid being posterized by a mega-dunker on defense.

    Still, it's awesome to see yet another statistical way to point out how fantastic Tim Duncan is, because he just doesn't get the credit he deserves.

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