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NBA HD: Analyzing Shot Location Matchups by Team

Last week, for my debut article here at Hardwood Paroxysm, I used shot location data from my mother site Hoopdata.com to see whether good shooting teams from a particular area from the floor enjoy an advantage against weaker foes in that shot location.  I found some compelling results; teams who dominate around the rim have generally shot better against weak post defenses, and vice versa.  I also discovered that a good three-point shooting team has not exhibited much of an improvement between facing a poor 3-point defense and an average defense, which was the only area to show that type of diminishing return.  So a team like the Suns, who terrorize opponents from downtown, may not see their deadly shooting talents magnify against a poor three-point defense.

My findings provided enough juice to take this a step further.  This time, I’d like to amp up the focus and look at specific teams this year.  I replicated the method I used last time and grouped the teams in tens depending on their opponent field goal percentage in each shot location.  I tossed the top ten teams into the “Good” pile, the bottom ten in the “Poor” pile and the rest in between were classified as “Average”.  You can find all this good info in the team shot location pages over at Hoopdata.  If you’ve read my work before, you know I really, really love adding colors to charts and graphs.  Each color has been formatted like a heat map to correspond with their relation to the group norm.  Looking at the FG% column, green fill illustrates a team’s excellent standing in that particular area and the opposite holds for red fill.  As it follows, yellow fill indicates a number close to the norm.  For the FGA column, the gradient ranges from yellow to burnt orange.   The colors should help you identify the extremes and digest the numbers faster.  The following chart shows how each team performs at the rim (layups, dunks, and tip-ins) when facing a good, average, and poor defense in the same area.

We’ll start with the Cavs.  They don’t miss at the rim, no matter who they face.  Led by LeBron James’ 73.8 at rim FG%, the Cavs shoot better at the rim against good defenses than 21 teams fare against poor ones. They shot 19-24 vs. the Lakers on Christmas Day.  In their two games against the 5th-ranked Pacers at rim defense, the Cavs nailed 30 of the 39 attempts at the basket.   LeBron’s finishing abilities are contagious in the sense that he pulls help defenders toward him as he drives, opening up easy buckets for his teammates cutting to the rack.

Looking elsewhere, the Raptors and Spurs are the only other two teams who finish above-average against all three groups while the Bobcats, Nets, and Bucks struggle against all defenses.  The Celtics wilt before top at rim squads but otherwise, they finish with gusto.  A lot of their problems at the rim would be solved if they never have to face the Magic.  In three of their four games against the Magic this season, the Celtics have missed 42 of their 73 chip-ins.  Granted, the Magic have the best post defense in the league but we’re talking layups here.

Do teams take more shots against poor defenses?  Not many, if at all.  On average, teams shoot 25.7 shots at the basket against good post defenses which is only one fewer than the rate against lesser defenses.   So the difference is marginal on the whole.  Interestingly enough, the Lakers don’t seem to be taking advantage against the weaker teams and actually take fewer shots at the rim in those scenarios.  Their .610 field goal percentage against poor defenses ranks 6th-worst in the NBA.  Kobe Bryant, who shoots 57.5 percent at the rim,  shares some of the blame for the Lakers woes.  He is actually a below-average finisher at the basket compared to his shooting guard positional comrades who average 59.8 percent.

Moving away from the basket, let’s take a look at how teams shoot on long twos.

Despite experiencing a sizable 22 point advantage in field goal percentage, teams don’t really look to take more long twos against poor perimeter shooting teams; teams average 0.4 fewer long twos against poor defenses than their portion against good ones.   It’s harder to distinguish between a good defense and a poor one in this range because the spread is so small.  The 10th best long two defense allows 40.2 percent whereas the 10th worst allows 38.6 percent.   Not a huge difference.

Nonetheless, some teams have really struggled against good perimeter teams.  Houston plummets from a healthy 42.2 FG% down to a league-worst 34.6 FG% as the going gets tougher.   Although, their distaste for long twos keeps that damage to a minimum; they take the second-fewest long twos in the game

It’s hard to fathom how difficult it is to shoot nearly 50 percent from this range but the Mavericks somehow manage to do it against bad perimeter defenses.  Led by long two resident Dirk Nowitzki, the Mavs have shot 50 percent or better 17 times this season from that area.  The Bulls?  Three times.  And they take average eight more heaves per game.

Let’s move along to our final destination: behind the three-point line.

Just as we saw with long twos, teams don’t tend to take more threes against poor 3-point defenses.  In fact, teams on average attempt more shots beyond the arc against good defending foes (18.3) than the average (17.3) and poor (18.2) opponents, despite knocking them down at a higher rate.

The Cavs are on top of their game in the most efficient areas on the floor.  Just as they were unfazed at the rim, Cleveland shoots well from downtown no matter who they face.  Not all 3-point shooting teams weather the storm like the Cavs however.  Contrast the Cavs with the Suns, another sharpshooting team, whose three point shooting numbers fall from .428 to .379 as their opponent improves.   Count Denver in that group, too.

With a .454 field goal percentage beyond the arc against poor 3-point defenders, the Spurs effectively shoot .681 with the added one point bonus.   That’s an amazing figure considering it’s more than 100 percentage points above the rest of the league, in terms of effective field goal percentage.  If the perimeter exploitation continues, the Spurs hope to draw either the Suns or Mavericks  come playoff time as they both rank among in the bottom ten in 3-point defense.  Otherwise, the Spurs are a below-average shooting team from beyond the arc.

While teams enjoy an advantage against the different quality defenses, they don’t launch more from the perimeter depending on their opponent.  Since the likelihood of nailing a shot from downtown is much smaller than at the basket, the perimeter ranks may be more random variation than true representation of strength.

Curious about the short and mid-range numbers?  Take a look at them here and here.  I saved them for the sake of  space but they’re definitely worth a look.

NBA HD: A Closer Look At Shot Locations

Hi, my name is Tom Haberstroh.  I write over at Hoopdata.com about the NBA and occasionally perform statistical magic over at ESPN Insider.  I have two middle names and enjoy watching Serge Ibaka play basketball.  Chris Paul, Randolph Childress and Muggsy Bogues went to my alma mater and my favorite Crayola color is jungle green.

The topic of interest in my first piece here at Hardwood Paroxysm centers around team shot location.   At Hoopdata, we track how teams shoot from five different areas of the floor: at the rim (layups, dunks, and tip-ins), less than ten feet, 10-15 feet, 16-23 feet, and beyond the three-point line.  There you will discover, among other things, that the Chicago Bulls take an outrageous number of long twos and the Washington Wizards’ defensive unit practically ushers the ball through the basket on shots at the rim.  Today, the statistic I am particularly interested in is shot location field goal percentage.  More specifically, if a team is horrible at shooting around the basket, how much worse does it get when they face a team that protects the rim?

Take, for example, Monday night’s matchup between the Milwaukee Bucks and Orlando Magic. The Bucks are just about the worst team in the NBA when it comes to converting shots at the rim as their 56.0 FG% from there ranks 29th in the league.  Dwight Howard and the Magic have the very best opponent at rim percentage (55.1 FG%).  So, what happened? The Bucks missed 11 of their 20 shots at the rim while getting swatted eight times on the evening.  And for the just the third time all year, Brandon Jennings didn’t take a layup all game.  I wondered if this was a typical performance for a poor-rim offensive squad taking on a stellar rim-defense and whether this opposite holds true when the tables are turned.

To shed more light on my curiosity, I ranked each team of 2009-10 by their field goal percentage from each area and separated the league into thirds depending on rank in the category.  Teams ranked 1-10 get tossed in the Good bin, 11-20 into Average, and 21-30 into Poor.  You may have seen this filing method before over at 82games.com.  So for example, the Chicago Bulls offense ranks 30th at the rim (Poor), 7th from less than 10 feet (Good), 5th  from 10-15 feet (Good), 28th from 16-23 feet (Poor) and 14th from 3-point (Average).  I then gathered every game (over 1,400 matchups in the sample) and calculated the field goal percentage in each shot location area.  So, on average, what happens to a poor at rim defense when it faces a good at rim offense? Let’s take a look.

I’ll walk you through this.  Defenses are separated by columns and the offenses are separated by rows.  At the end of each column and row, you’ll find the average for that group.  Ignoring the intersections for the moment, you see that the collective Good defensive group allows a .578 field goal percentage on shots at the rim and good offensive teams average .635.  Now when they meet (say, when the Cavaliers, a Good at rim offense, faces the Celtics, a Good at rim defense), the Good offense shoots 61.3 percent from the area, on average.  With me? I’ll take that as a yes.

As expected, teams perform better if their opponent defends worse in that area.  The empirical evidence confirms our intuition.  The Bucks-Magic matchup represents an extreme case on both ends,  so the Bucks’ 45.0 FG% makes sense.  On the other end of the spectrum, a good offense will dominates the poor defense, converting almost 2-out-of-every-3 shots at the basket.  Interestingly, a poor defense will make a poor offense look average by comparison and a good offense will make an average defense look poor.   Let’s take a look at shots inside 10 feet (not at the rim).

We see much of the same trends here in this one.  It really hurts to be a poor in this area offensively going up against a good defense.  Despite the near proximity to the basket, poor teams shoot  36.6 percent against good squads or roughly the same as the typical squad shoots from downtown.   This zone gets about a third less shot traffic compared to the at rim zone, so the results will be more varied in one-game snap shots.   How about the 10-15 feet area?

It doesn’t really pay all that much to be a good offensive team going against a good defensive team from the mid-range; the good and average offenses are nearly identical on average (.379 vs. .380).  That’s the first time we’ve seen such a case.  The typical team only gets about 7 shots per game from this area, so the numbers here will tend to exhibit more statistical noise.  Nonetheless, if you’re facing a good defense in the mid-range, don’t expect your shots to drop no matter how well you normally shoot from there.  Let’s take a look at what we see from the least efficient area of the five: the long two.

Long twos are much more stable than the rest of the fields we’ve looked at.  The spread between PoorO-GoodD and GoodO-PoorD is only 68 percentage points whereas in the  previous ranges the spreads were 111 at the rim, 139 from short, and132 from mid.  But this follows the bigger picture.   A good long two shooting team isn’t a whole lot better than a bad one.   However, if you can’t normally knock down long jumpers inside the three point line (attn: Bulls), don’t get too  excited when you face a bad defensive team on the perimeter.  You’re still probably going to miss more than 60% of your shots from there.

Interestingly enough, a good defensive squad in this area has the opposite effect compared to the mid-range.  Compare the good defense columns.  Field goal percentage against good defenses actually increases from .366 to .380 as you migrate further away from the mid-range to long-range twos.  Either a good mid-range D is especially suffocating or a good long-range D doesn’t amount to much in the end.   A third explanation could be that the low sample size of mid-range shots on a game-by-game level produces some whacky results.   And finally, moving onto the three point line.

For the purpose of staying consistent, I’ve presented the three-point numbers in field goal percentage as opposed to effective field goal percentage.  Just keep in mind that even though the most advantageous situation yields only a 37.9 FG%, the added bonus of 1 point makes a world of difference.  And much like shots from 16-23 feet,  the spread between the best and worst intersection is only 73 points.  Take a look at what happens when a good three-point shooting team goes from an average opposing defense to a poor one.  The percentage actually decreases on average from .386 to .379.  Good shooters from a particular area tend to improve across the board, however, from beyond the arc there doesn’t seem to be a discernible advantage.   I’d only be speculating as to why this might be the case, if there is in fact a real effect here, but it could be that the difficulty of three-point shooting caps the shooter’s ceiling.  The best shooting teams from long distance can only shoot so well since the threeball rarely goes in to begin with.

Like most studies, there’s plenty of room for more digging and statistical analysis.  The logical next step would be to gather the variability, or standard deviations, of the  presented figures.  That way, we can see the overlap and strengthen our expectations.  In this piece, I analyzed the league on a macro level but I could take this in other directions as well.  How does each team perform against the various defenses?  Moreover, do good shooting teams take more shots in areas where they have the upper hand?  I’ll have to save those questions for another time.  But for now, it does appear that teams experience greater success if the defense is weak in a particular zone.  So keep these numbers in mind as you prepare for your team’s next game.

Stay tuned for more shot location analysis in the future editions of NBA HD.

If you can’t knock down long jumpers inside the three point line (attn: Bulls), don’t get too  excited when you face a bad defensive team on the perimeter.
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