The Oklahoma City Thunder had issues on defense last season. It lost defensive player of the year candidate Andre Roberson for the season, while Carmelo Anthony’s offensive gifts couldn’t cover up his shortcomings on the opposite end.

Things got much worse in the playoffs. In the Thunder’s series against Utah, the Jazz constantly targeted Anthony by running as many pick-and-rolls to get him in mismatches. In the 194 minutes Anthony was on the floor in the series, he had a defensive rating of 108.2. The team improved to 94.9 when he was off the court, a massive swing. To make things worse, he wasn’t bringing anything on the other end, providing an offensive rating of 95.6. It was clear heading into the offseason that Anthony was not a piece the Thunder can depend on so he was traded to the Atlanta Hawks, who subsequently bought him out. Anthony wasn’t the only problem with the Thunder defense: It was all too common for Oklahoma City players to just not help out teammates.

This year, things are different.

Coach Billy Donovan now has the defense moving on a string and always ready to rotate, making the Thunder appear to be the top team that can contend with the Golden State Warriors in the West.

Surprised? You shouldn’t be.

Paul George, who has made three all-defense teams in his career, is returning to the two-way player he was in Indiana, while Russell Westbrook has also put much more effort in defensively. Against the Detroit Pistons, Westbrook switches onto Blake Griffin and immediately fronts him. This forces Steven Adams to come over the top and as he does so, the weak side has to pull over, which it does. They take away Drummond then work their way out, as Griffin has to take a difficult fadeaway. They do it again — when Terrance Ferguson doubles the post, as the ball gets kicked out, he flies to the corner to take away the three. He gets beat baseline but Adams steps up to help him and George drops to take away the pass to Drummond, which forces a turnover.

Almost everyone who played for the Thunder in 2017-18 and is also getting major minutes this season has improved their individual defensive rating. Even Dennis Schroder’s defensive rating has dropped from 110.8 with Atlanta to 99.8 this season with Oklahoma City.

Defensive improvement of the Oklahoma City Thunder

The removal of Anthony from the roster allowed the Thunder to insert Jerami Grant in the starting lineup. As his minutes have increased from 20 to 30 a night, he has delivered for Donovan. Grant gives the team another rim protector to pair with Adams. The team has a net rating of plus-11.7 when he is on the court versus a minus-4.6 when he’s off. Being able to give Grant more minutes has made the defense even stronger.

Yet the biggest change is in Oklahoma City’s three-point defense, which has cut down the amount of wide-open three-point attempts against, defined as the closest defender six feet or more away. Last year, the Thunder ranked fourth for most wide-open three-point shot attempts against per game (16.2), which accounted for a league-high 21 percent of all their opponent’s long-range attempts. This year, it is ninth in both frequency (16 percent of shots against are from beyond the arc) and attempts (14.3 three-point attempts against per game), and that makes this Thunder team better defensively than the one that challenged the Warriors last year.

All roads to winning in the NBA go through the Warriors and that means having to defend the three-point line. The Warriors shoot 39 percent from deep and have three guys that can catch fire in a heartbeat. The number of their attempts from three is vital to stopping them. In their nine losses this season, the Warriors have averaged 28 attempts compared to their 32 in their wins.

The Thunder have improved in that area from allowing 36.7 percent from three last season to 32.6 percent this year, good enough to place in the top five of this category.

In the earlier clip, Ferguson took away the corner three away from the Pistons. Here is another example of rotating defensively to a three-point shooter. Westbrook does his job in taking away the layup on the Denver Nuggets’ back cut, which triggers George to rotate to the corner to cover for Westbrook as Grant gets George’s man. He gives a great contest on the three-point attempt. This is the type of rotation that they missed several times over last year is the key to the Thunder beating the Warriors.

Oklahoma City has the best defensive rating in the NBA with improved focus up and down the roster on that end. Even more impressive is that the team is doing this without its best defensive player, Roberson. If he can return back to form, he can raise the Thunder’s ceiling even higher.

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