Big men who protect the rim like mother lions guarding their offspring will always be important. But long, athletic wing defenders have become the league's next most valuable asset in preventing opposing teams from scoring—especially in the Eastern Conference, where scoring swingmen are plentiful.
With Paul Pierce's lateral quickness declining by the day, the Celtics snatched Green from Oklahoma City primarily because they needed someone to defend LeBron James for heavy minutes in the postseason. (This also applies to Carmelo Anthony, Joe Johnson and Paul George.)
If the Celtics are to make any relevant noise in the playoffs, they'll need Green to do amazing individual work on the defensive end. The task of hounding the world's best players is preposterously difficult, but Boston's biggest X-factor has actually held his own this season.
According to NBA.com/Statscube, James is averaging 27.5 points per 36 minutes against the Celtics this season with Green on the bench and 26.0 when he's on the court. No real difference in the scoring numbers, but the shooting percentages really take a tumble.
With Green on the bench, James is shooting 56 percent from the floor and 67 percent from behind the three-point line. With Green on the floor, those numbers drop to 48 percent from the floor and 25 percent (!) on threes.
The sample size is tiny, and Green isn't necessarily assigned to cover James every single possession the two share on the court, but that doesn't mean the decrease in James' efficiency should be completely dismissed. The word "contain" shouldn't be used to discuss any one person on the planet defending LeBron James, but from a physical perspective, Green does as good a job as anybody matching up with him.
Here is Green making James uncomfortable on two separate isolation plays.
Carmelo Anthony, a more realistic playoff opponent who poses nearly as many problems for Boston's defense, is averaging 26.8 points per 36 minutes on 44 percent shooting this season. But when he plays the Celtics and Green is on the court, those numbers fall to 19.5 points and 32 percent, per Statscube.
Look how Green bodies him closely, preventing Anthony from firing a nightmarish jumper and forcing a drive to which he's athletic enough to contest.
As an aside: In his first season as an All-Star, Paul George has averaged 6.3 points per 36 minutes on 17 percent shooting while sharing the court with Jeff Green this season.
The sample sizes here are all very, very small. And as of today, there's no way to statistically quantify just how important the other four defenders Boston has on the court beside Green are in making great scorers work for their points.
But this season Green has shown an ability (on the ball, at least) to make life difficult for the world's best players while they're looking to score.
According to Synergy, Anthony has score in five of 15 possessions where Green is his isolated defender. By comparison, James scored the exact same number of times, not including two possessions in which Green fouled him, out of 15 plays.
Overall Green allows 0.71 points per isolation possession, good for 65th in the league with opponents scoring 37.9 percent of the time.
When the playoffs start, Boston is guaranteed to be matched up with either the New York Knicks, Indiana Pacers, Miami Heat or Brooklyn Nets in the first round (the latter half of teams being drastically less likely than the former).
All of them boast a forward capable of taking over games on the offensive end, and this is where Green becomes especially important. The Celtics find themselves in relatively good hands when it comes to making life harder for players like LeBron James and Carmelo Anthony, but sustaining that stellar defense over the course of a seven-game series is nearly impossible.