It's defense that makes 'Playoff LeBron' a thing

It's that time of year again.

As the NBA playoffs loom, it's time to commence talking about LeBron James "flipping the switch" and transforming from regular-season LeBron into playoff LeBron before our very eyes. While it's true that some of the metamorphosis has to do with an increase in minutes -- regular-season LeBron plays 37 minutes a game to playoff LeBron's 42 -- James' impact is about a lot more than playing time.

In fact, while many will focus on his scoring and offensive impact in the coming weeks, the switch that James flips should be labeled "defense." Defense on the ball. Help defense. Transition defense (Andre Iguodala can explain this to you). All kinds of defense.

Because the real difference between the two LeBrons has been felt on the defensive end, basic statistical measurements have had a hard time accurately capturing the magnitude of the flipped switch. With the massive data from Second Spectrum, however, each aspect of LeBron's defensive impact can be measured and understood at a deeper level.

Starting with the 2013-14 season, Second Spectrum has tracked the location of everything that moves on a basketball court at a rate of 25 times per second, and with this data, each aspect of LeBron's game -- and, in turn, his impact on the Cleveland Cavaliers competing for a title in 2018 -- can be broken down and measured.

Trying harder in the half court

Let's start with LeBron's on-ball defense. During the regular season, when LeBron is the primary defender, opponents attempt shots with an average quantified shot quality (qSQ) of 53 percent. This means an average NBA shooter, given the same shot type, level of defensive pressure and location, would have an effective field goal percentage (eFG) of 53 percent on shots taken against LeBron. In the regular season, shooters have an eFG percentage of 49 percent on these attempts, meaning they shoot about 3.5 percent worse than average when regular-season LeBron is guarding them.

Against playoff LeBron, shots of the same average quality have an eFG of 47 percent, or 5.5 percent worse than average. Playoff LeBron is more effective than regular-season LeBron at reducing his opponents' ability to convert shots, and he's more effective in part because he contests 4 percent more shots per 100 possessions in the playoffs than he does in the regular season.

Help is on the way from LBJ

Playoff LeBron is a more active and effective team defender than regular-season LeBron. When one of James' teammates is defending an opponent's drive to the hoop, regular-season LeBron helps on 7.5 percent of those drives, giving up 0.95 points per drive when he helps. Playoff LeBron helps on 11 percent of drives, with his team allowing 0.9 points per drive. LeBron's regular-season efforts would rank his team as roughly the 12th-best defensive team against drives in the league -- playoff LeBron's teams rank No. 1 in this area.

Getting back on the break

Playoff LeBron is also a far more effective defender in transition than regular-season LeBron. On transition possessions that LeBron is involved in during the regular season, his team gives up 1.3 points per possession. During the playoffs, however, when James is part of the transition defense, his teams give up an average of only 1.1 points per possession. For some perspective on how big that difference is, regular-season LeBron's transition defense puts his team as one of the five worst transition defenses in the league, while playoff LeBron's transition defense would rank his team as the best transition defense in the league, and by a good margin.

The Cavaliers have never needed playoff LeBron more than they do this season. The Cavs have the 29th-ranked defense in ESPN's Basketball Power Index, which puts their odds of reaching the NBA Finals at 3.9 percent -- well behind the Raptors (58 percent), Celtics (21 percent) and Sixers (11 percent). Without a significant switch-flip from LeBron, the Cavs' defense is simply not good enough. If James is going to extend his personal NBA Finals streak to eight, it will be because playoff LeBron again showed his face.

All data used is provided by Second Spectrum and NBA Advanced Stats.

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