The Utah Jazz defensive performance over the past 23 games is hard to grasp.   The defensive numbers have rarely been seen for an extended period of time in the NBA.    The next best teams in the NBA aren’t even close to achieving what the Jazz are doing defensively.    Interestingly, the key to the defense is not as much defending the shot, but where the Jazz are forcing shots to be taken.

For the season the Jazz defensive rating (pts allowed per 100 possessions) is 101.7.   Over the past 23 games, when the Jazz have won 21, the defensive rating is 94.5, the next closest is 103.0.   The Jazz compared to the Top 10 since Jan 24th when the Jazz started this stretch is stunning.

Usually, when a team is this far off the charts there is something unusual taking place.  In a make or miss league that means the opponents are missing and a team is being fortunate.   In this case, the margin is so significant something different is taking place.

The Jazz are getting a bit fortunate.   On the above the break 3 point shot opponents are only making 30.3% of their attempts.  The league average 35.8%.  An argument can be made that the Jazz disturb the offensive rhythm of teams to the point where these are uncomfortable shots and are more likely to miss.

In the other areas of the floor, the Jazz defense is doing what it has done all season long.  In the restricted area teams are shooting 61.2% and for the season shot 62.5% v. the Jazz.  In the paint non-restricted area, they are shooting 36.3% and for the season 37.5%.  From the mid-range teams are shooting 37.5% and for the season 39.6% and on the corner 3, which the Jazz allow the fewest in the NBA, teams are shooting 40.5 % and 40.1% for the season.

There are slight upticks here and those are easily explainable by the games missed by Rudy Gobert and his return.

Where the Jazz really thrives is the opponents shot composition.    Over the last 23 games, the Jazz have taken away the most efficient shooting areas from their opponents.  Teams average 1.26 pts per shot in the restricted area.  The next most efficient spot is the corner 3 at 1.18 pts per shot.

Teams are only taking 27.3% of their shots in the restricted area, the league average is 31,7% of attempts.   Opponents are only taking 5.1% of their shots as corner 3s and the league average is 7.1%.   Moneyball shots are at the rim (restricted area) or three-point shots.   65.4% of all shots come in those two areas, against the Utah Jazz only 57.3% of shots come in those areas.   Shots in non-money ball areas, paint non-restricted area or mid-range, average just .8 points per shot.

When Rudy Gobert is on the floor this is even more dramatic.  Opponents take just 26.5% of their shots in the restricted area and 4.9% of their shots as a corner 3 attempts.

On average the Jazz opponent is taking 21 shots from the above the break three a night.  In this recent stretch at 30% they are making just 6 of those attempts.  If they return to the league average of 36% they would make on average 1.5 more threes a game.

That would add about 4.2 pts per 100 possessions still leaving the Jazz defensive rating at 98.7.   Under this regression to the mean, the Jazz defense is still nearly 5 points better than the 2nd best defensive team.

The Jazz defensive system anchored by Rudy Gobert is not only good at defending shots it is forcing inefficient shots at a higher rate than nearly any defense in the NBA.  For that reason what the Jazz are achieving defensively right now has every reason to be sustainable.