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How Bad Has the Defense Been?

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We all know the Sixers defense has been terrible. The only thing I've been struggling with is quantifying just how bad it's been through the first 20 games of the season. My gut tells me it's been tragically bad, especially when compared to what we've seen from this team over the past two seasons. After the jump I'll use a mixture of basic and advanced stats to try to paint a complete picture for you of where this team stands defensively. (If statistical analysis bores the living daylights out of you, I've summed up each dorky analysis section with a mini conclusion, then there's a wrap up of the whole exercise at the end. Glance at the charts and graphs, then the conclusions and you should get a pretty good picture).

I apologize in advance for the length of this post. Once I started digging into stats, one thing led to another, honestly it could've been much longer. If you get bored just look at the pretty pictures and skip to the conclusion sections.

A few words about my methodology first. I took every Sixers opponent from this season (17 teams, 2 games vs. BOS, NJN and CHA), I scraped their game logs from B-R.com, then segregated the stats from their game(s) against the Sixers. The goal was to compare how each team played against the Sixers vs. how they played against the rest of the league. I also used the standard deviation on certain stats, without segregating out games played vs. the Sixers, to give an idea of the scale of the numbers, more on that part where appropriate.

Let's start off with a series of tables before we dive deeper into the stats. These tables show every opponent the Sixers have faced, how they performed in key statistical areas when they faced Philly, how they fared in those same areas in games played against everyone except Philly, and the difference between the two numbers. What we're looking for here is how the Sixers fared vs. all these teams in comparison to how every other team they've faced has fared defending them. 17 opponents over 20 games (offensive rating is the opposing team's points scored per 100 possessions, O-Reb % is the percentage of available offensive rebounds the opposing team grabbed, eFG is essentially a measure of field goal percentage with three-point shots taken into account):

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Alright, now that we have all these numbers in front of us, let's take the long view for a second. We'll just list out the number of matchups the Sixers have out-performed the average in the key categories (PPG, 3P%, eFG, O-Reb%, Off. Rating). Keep in mind, we are only looking at the Sixers defensive numbers, a win means they were better than the average, a loss means they were worse than the average. So a loss in eFG doesn't mean the other team shot better than they did, only that the other team shot better against the Sixers than they did against the other teams they've played.

  • Points-per-game: 6 wins, 11 losses
  • Three-point percentage: 5 wins, 12 losses
  • eFG: 2 wins, 15 losses
  • O-Reb%: 9 wins, 8 losses
  • Offensive efficiency rating allowed: 3 wins, 14 losses
We'll dive a little deeper into these numbers further down, for now, just let them soak in.

Let's take a step back and look at a very basic stat:

Three-point percentage

  • vs. the Sixers: 41.19% (166/403)
  • vs. others: 34.76% (1,914/5,506)
  • difference: 6.43%

The Sixers are dead last in the league in three-point percentage allowed, 3.6% worse than the #29 team (Memphis), 11.4% worse than the best team (LA Lakers). League average is 34.99%, with a standard deviation of 2.5% (Basically, standard deviation is a statistical barometer that's used to determine if a variance is significant. Here's a good rule of thumb, if you're within one standard deviation of the average, you're basically average, give or take. If you're between one and two standard deviations, you're skewing pretty heavily either way. If you're more than two standard deviations away, you're an outlier, for better or worse, or to put it bluntly, among either the best or the worst, and not even close to average).

In this case, 20 of the 30 teams are within one standard deviation of the league average for three-point percentage allowed, 66.7%. 28 teams are within 2 standard deviations of league average, 93.33%. Only 2 teams are more than 2 standard deviations away from league average, the Sixers on the low end and the Lakers on the high end. In other words, the Sixers are far and away the worst three-point defending team, and they aren't even close to respectability. They aren't merely a couple hot nights away from mediocrity, they're more than a full standard deviation away from the #29 team. Apply that logic to the differential above, and you can start to grasp exactly how much worse the Sixers have been at defending the three than the other teams their opponents have faced.

Mini conclusion: Their 3P% against is the worst in the league, and by no means is it a result of them playing against excellent three-point shooting teams. It's a huge, huge problem.

Circling back to the stats we broke down by opponent earlier, I'd like to take a closer look at two areas: eFG and Defensive efficiency rating. eFG incorporates three point shooting and defensive efficiency rating incorporates everything. Here's a game-by game look at each, starting with eFG:

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We already know the Sixers have underperformed in this category on a regular basis, this chart shows us the degree of their ineptitude. Overall, the Sixers rank 28th in the league in eFG allowed. The league average is 49.67% with a standard deviation of 2.1%. On the year, the Sixers are 1.76 standard deviations away from the mean at 53.3%. The league leader in eFG allowed is the Lakers, again, at 46%, so the Sixers are roughly 3 standard deviations away from the #1 team, and a little over 7% in raw eFG. Keep those numbers in mind and take another look at the graph above. (I'm going to use this standard deviation as a barometer, even though I realize it isn't a one-to-one correlation with the data below. You'd have to get the eFG allowed for every single game to figure out the exact standard deviation for these numbers and I don't have the time to run through all those numbers. I'm going with this standard deviation because it's handy and gives you a decent scale to work with).

The Sixers had one game where they significantly out-performed their opponent's other opponents, the Bucks game. They had two games where they were within one standard deviation of the norm on the positive side, four games within one standard deviation of the norm on the negative side, three games between one and two standard deviations on the negative, and a whopping ten games where they were more than three standard deviations worse than the norm. That's simply astounding. Think about it, the difference between the Sixers eFG allowed and the average eFG allowed for their opponents was greater than the difference between the season eFG allowed for the Sixers (#28) and the Lakers (#1) seven times in 20 games. It was more than twice that difference on two separate occasions.

Mini conclusion: Simply put, teams absolutely shoot the lights out against Philly. It's not just three-point shooting, either. Four different times the Sixers held an opponent below their average 3p%, but still they allowed a much better eFG than the team's other opponents. Open threes, drives to the hoop for uncontested layups. We've seen the reasons for these numbers with our own eyes, this graph just backs up what we already knew, and adds some depth to the argument.

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For my money, defensive efficiency rating is the holy grail of team defensive stats. It encompasses pretty much everything: Shooting, rebounding, fouling (both in a good and bad way), forcing turnovers. I'll give a brief description which should hopefully illustrate exactly how meaningful this stat is.

Each game is essentially a series of possessions, a possession can only end one of three ways: (1) Turnover, (2) Made basket (or free throw), (3) Defensive rebound/blocked shot + securing the ball. That's it. Offensive rebounds simply extend the current possession. The  ultimate killer would be an and-one followed by a missed free throw, followed by an offensive rebound followed by a made three-pointer. That would be a five-point possession. Obviously, you could go on from there with another foul on the shot, etc. Typically, though, 3 points is the most you're going to come out of a single possession with.

I could talk about this all day long, but essentially a good defensive team will limit the situations where the percentages say a team will score more than one point. A 40% two-point jumper with your team in good defensive rebounding position is an excellent defensive possession, worth roughly 0.8 points. An open three for a guy shooting 40% from down town is a bad defensive possession, worth roughly 1.2 points. Giving up an uncontested dunk is probably worth close to 2.0 points, so fouling a guy hard when he's going to throw a dunk down would statistically save your team .6 points if the guy is a 70% free throw shooter (0.7 points on each shot from the line, 1.4 points). Fouling a three-point shooter is an unforgivable sin, even if he's a 40% shooter from downtown, you're talking about 1.2-point possession. If you foul him, again assuming he's a 70% shooter, you've just upped it to a 2.1-point possession. Any foul on a jump shooter is completely stupid, no exceptions. 

The best defensive team in the league (currently Boston) allows 0.991 points per possession. Defensive efficiency rating is simply that number multiplied by 100, I believe so the rating could resemble a stat everyone (old school media) is familiar with, points per game. The Sixers defensive rating on the season is 112.66 by my math (B-R.com uses different metrics). Over two full standard deviations (2.5) from the league average (106.6).

The chart above this wordy explanation depicts the differential between the Sixers defensive efficiency rating in each game versus their opponent's offensive efficiency rating in all games played against teams other than the Sixers. A zero would mean they defended their opponent as well as all the other teams did. A positive number means they were better defensively than the average, negative means they were worse. It's not a pretty picture.

There is one outlier on the positive side, the Milwaukee game.  Other than that game, only once was their differential meaningfully positive, in game 8, their second win against the Nets. They were within one standard deviation on the positive side on two other occasions, both losses. Game 6 at Detroit and Game 10 at Chicago. Those are the only two games which you can legitimately say offense cost the Sixers the game.

The other 16 games vary from negligibly bad defense (Within one standard deviation on the negative side: Gm 11 - win over Charlotte. Gm 13 - loss to Cleveland. Gm 16 - loss to Atlanta), to notably bad defense (Between one and two standard deviations: Gm 12 - loss to Memphis. Gm 17 - loss to San Antonio. Gm 18 - loss to Dallas) to the pitiful (More than 2 standard deviations: Amazingly, they won two of these games with huge negative differentials. The other seven were predictable losses) finally to the completely horrific (Against the OKC Thunder, the Sixers were 10 standard deviations worse in differential. They made a decidedly inefficient offensive team look like a juggernaut, allowing an astounding 27.99 more point per 100 possessions more than the mean).

I think this graph supplies an easy answer to the question, "Why are the Sixers 5-15?"  They're 5-15 because they simply cannot defend anyone. We need to take a holistic approach to these numbers to answer figure out why they can't defend, though.

Mini Conclusion: The Sixers, as currently constructed and coached, simply cannot compete on the defensive end of the floor. They are getting routinely dominated to the point where even when they have outstanding offensive games, they still cannot make up the deficit their defense creates. Look at it this way, if you want to break down their five wins, the defense legitimately won two games for them (MIL, NJN), their offense made up for shoddy defense in three other games. If you want to break down their losses, twice the offense couldn't support an average defensive effort, and 13 times the defense was so atrocious the offense would've had to perform unbelievably well to compensate for it.


Final Conclusion: Three factors have conspired to make the Sixers such a horrible defensive team: open looks at three-point shots, easy two-point opportunities and shoddy defensive rebounding. All three problems can be traced back to two fundamental flaws (1) A crazy rotational scheme, which is responsible for the open looks from three and the high percentage on twos. Players just get open way too easily against this team because of the over-helping. This also leaves players out of position for defensive rebounds when the scheme actually works, extending possessions. (2) Small lineups, with weak defenders at multiple positions. This affects the numbers in two ways. First, it creates mismatches, which stress the fundamentally flawed defensive system, creating high-percentage looks from all over the floor. Second, it puts weak rebounders in even more unfavorable rebounding matchups, opening the door to a slew of offensive rebounds for the other team.

Put simply, the Sixers system and lineups set them up to fail in two key defensive areas, and they also compound the problem. Even if a team has a bad shooting night, they're able to make up for it in efficiency by dominating the offensive glass. The things the Sixers do well on the defensive end (creating turnovers and not fouling too much), rarely if ever make up for the tremendous deficit created by the problems listed above. If you need a concise five-word synopsis: Eddie Jordan Is To Blame.

I realize EJ's supporters will try to spin this and place the blame on the players, and while some blame should be shouldered by the guys who suit up, I figured we should take a quick look at what Mo Cheeks did with essentially the same roster last season. If you remember, Mo was fired 23 games into the season when the Sixers had a 9-14 record. Take a look at this chart, then we'll talk below.

isitcoach120709.jpg This time last year, when the Sixers fired Cheeks, essentially for not being able to integrate Elton Brand on the offensive end, he had them playing exceptional defense. He had each player in his ideal position (until his final two games when he hit the panic button and moved Green into the starting lineup). The team rebounded well, defended the three very well, forced turnovers and got stops. A good defensive system, coupled with playing smart lineups led this team to exceptional heights on defense.

If you'd like a further indictment of Eddie Jordan, Tony DiLeo took over for Cheeks midstream and used a small lineup for the remainder of the season when Elton Brand went down. That team out-performed Jordan through his first 20 games in every meaningful category even though he never even had the option of using a big lineup.

Preview will be up later in the afternoon, have at it in the comments.