Defense wins championships. At least, that is the saying for the NFL. But does this apply to basketball? When we think of the greatest teams of all time, we love to think about offense. We think about the showtime Lakers with Magic leading the fast break, the Jordan era Bulls with MJ's signature dunks and offensive arsenal, and the recent Golden State Warriors featuring some of the most lethal offensive players of all time. But we don't really think about defense. No one will ever remember the Warriors for the defensive versatility of Draymond Green. But why not?
Here are a couple of charts comparing offensive and defensive rating to team success from last regular season:
These two charts are both showing the correlation between win percentage and offensive or defensive rating. The win percentage is adjusted to compare to league average, so 0% would be a 41-win team, 50% would be a 61.5-win team, and -50% would be a 20.5-win team. The offensive and defensive ratings are also adjusted to be a percentage compared to league average (which was 110.6). Just looking at these graphs, you may think they look fairly similar. However, what I want you to focus on is the equation of each of the lines of best fit. These equations allow us to evaluate correlation and predict win percentages based on offensive or defensive rating. The equation for offensive rating is y = 13.617x - 0.0173, and the equation for defensive rating is y = 17.097 - 0.0172. The number that stands out as different amongst the two equations is the slope of each line. The slope tells us the change in y (win percentage compared to league average) when there is a one-unit change in x (offensive or defensive rating). The difference in slope tells us that defensive rating can swing a team’s success or failure at a much higher rate than offensive rating can. Translation: defense is more important than offense when it comes to regular season success. By a lot. Let's look at some examples:
Let's take a look at two teams, one that is +3.5 above the league average offensive rating and one that is +3.5 in defensive rating. Using the formulas from above, we can project the team with the +3.5 offensive rating will have a relative win percentage of +47.6422%, while the team with the +3.5 defensive rating will have a relative win percentage of +59.8223%. The first team would be projected to win 60.5 games, while the second team is projected to win 65.5 games. At the top of the league, five wins is a very significant difference. Now let's look at another example of two teams with a bad offense or defense. Instead of +3.5 for offense and defense, we will use -3.5. We can project the team with the -3.5 offensive rating will have a relative win percentage of -47.6768%, while the team with the -3.5 defensive rating will have a relative win percentage of -59.8567%. The first team would be projected to win 21.5 games, while the second team is projected to win 16.5 games. That's the difference between an average worst team in the league and an all-time terrible team. To summarize what we have just learned, a good defense is more helpful than a good offense in terms of winning regular season games, while a bad defense is more detrimental than a bad offense in terms of winning regular season games.
So, how can we apply this? Well, what teams should be doing is thinking about some of their offseason moves in this prism of thought. Defense can swing your team’s success more than offense can. A lot of people are very excited about the Atlanta Hawks, but they didn't get anyone who can really defend outside of Kris Dunn. That team is still going to have a terrible defense. Some of the worst defensive teams in the league did nothing really to address their defense and expect to somehow be far better next season. These teams include the Wizards, Hornets, Spurs, and Timberwolves. Some of the teams at the top of the league got worse defensively this offseason. These teams are the Lakers, Nuggets, and Bucks. Expect each of these teams to be worse come playoff time. One of the worst defensive teams in the league that did do a lot to improve their defense was the Portland Trail Blazers. Because of this, I think of them now as a potential three seed in that conference. The moves to pick up scorers may be flashier and more exciting for fan bases, but it is the pickups of Robert Covington, Josh Richardson, and Jae Crowder that can really determine the fate of a regular season.
We've talked a lot about the regular season, but this article is asking if defenses win championships. Here are a couple of charts to help answer that question:
These two charts show the exact same thing in different ways. These charts are showing the relative offensive and defensive rating of the past 16 NBA champions. I chose the past 16 champions because those are all of the champions after hand-checking was taken out of the game, which significantly increased offensive rating. The discolored spots on each graph show the overall average of relative ratings for the championship teams. As you can see, the average relative defensive rating is higher than the relative offensive rating. For defense, the average is +4.05 while for offense the average is +3.5. While that may not seem like a huge difference, last season that was the difference between the 8th and 12th best defenses, and the 7th and 11th best offenses.
So, does defense win championships? The short answer is yes. But so does offense. You don't really win championships without a good offense and defense. You can tell this by looking at both charts. Some teams win with great offense and above average defense, while some teams win with great defense and above average offense. I think it is interesting to look at some of the teams that were better defensively than they were offensively. First of all, last season’s Lakers were significantly better on defense than offense. Even though people are going to look back on that team and think about the offense of LeBron James, it was really the defense of Anthony Davis that made that team elite. The same can be said for the 2011 Mavericks. They were very close in terms of relative offense and defense, but all anyone thinks about is Dirk's shot making. The defense from Tyson Chandler, Shawn Marion, and Jason Kidd were just as important. Paul Pierce won the Finals MVP for the 2008 Celtics championship, even though it was Kevin Garnet and that teams defense driving the team to success. The Lakers of 2010 and the Heat of 2012 were actually better defensively than offensively. Despite this, people will only ever think of Kobe, LeBron, and D-Wade's offensive games instead of looking at the defensive impact of Trevor Ariza and Shane Battier. Basketball is far more than just putting the ball in the basket. Stopping someone else from putting the ball in the basket is worth just as many points. Teams need to really consider the impact every player will have at both ends of the floor when signing free agents, making trades, or evaluating how good they think their championship odds are. Us as outsiders should be weighing defense just as much as offense when looking at how good a team is. Defense is just as, if not more important than offense when looking at an entire team.
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