The Trail Blazers' early dominance has been one of the biggest surprises this season. Their offense has featured a potent blend of inside and outside weapons, facilitated by crisp execution. However, as good as their offense has been, their defensive performance has lagged behind.
As of December 11th, the Blazers were surrendering an average of 103.4 points per 100 possessions, putting their overall defensive efficiency in the bottom third of the league. Unbalanced excellence doesn't necessarily preclude playoff success, but the fact that their defense struggles leaves a big question mark hanging over their impressive record.
If we separate things out by lineups, things don't look quite as bad.
The Trail Blazers' starting five of Damian Lillard, Wesley Matthews, Nicolas Batum, LaMarcus Aldridge and Robin Lopez has actually been quite respectable defensively, surrendering an average of just 101.8 points per 100 possessions. Any time that group hasn't been on the floor together, the team has been allowing an average of 104.3 points per 100 possessions, a significantly worse mark.
One of the major problems with the Blazers' defense, regardless of which group of players is on the floor, is how the Blazers' big men are playing the pick-and-roll.
Their victory over the Jazz on Monday night was a perfect illustration of their issues in this particular defensive facet. According to mySynergySports (subscription required), the Jazz had 20 possessions finished by ball-handlers in the pick-and-roll, on which they scored an average of 1.35 points per possession.
On the season, the Blazers are allowing pick-and-roll ball-handlers an average of 0.81 points per possessions, 25th in the league. This inability to stymie penetration has led to breakdowns in other areas as well.
In general, the Blazers' strategy has been to have their big men sag into the paint instead of jumping out on the ball-handler.
This is the same basic strategy that the Memphis Grizzlies and Indiana Pacers use when defending the pick-and-roll, to great success. The idea is to keep the ball-handler out of the paint in favor of conceding more space in the mid-range area.
The problem is that Lopez and Aldridge haven't done a great job of balancing their responsibilities for containing penetration and still keeping themselves close enough to challenge a pull-up jumper.
You can see here, in the full possession, that Trey Burke simply takes the space Lopez gives him and knocks down the uncontested jumper.
Contrast that with the spacing of the Pacers defense on essentially the same high pick-and-roll with Burke. Hibbert is much closer to Burke and ends up getting a hand in his face as he shoots.
One of the reasons Hibbert is comfortable being that close on Burke is that he knows Paul George and Lance Stephenson are both in a position to help if Burke should try to drive past him.
The Pacers rarely get punished for giving up this pocket of mid-range space on pick-and-rolls because they know how to quickly squeeze that space with length, quickness and excellent spacing from their wings. What often looks like an open jumper against their defense, turns out not to be after the ball-handler has already made the decision to shoot.
The Blazers haven't figured out how to balance allowing the space but still restricting what teams do with it. Their opponents aren't just exploiting this space against jump shots by pick-and-roll ball handlers, they're also taking advantage of subsequent defensive rotations to create good shots for other players.
Here, the Blazers' defense is actually in fairly good position defending a pick-and-roll between George and David West.
But George patiently dribbles laterally pulling both Aldridge and his defender, Batum, with him. The third defender is afraid to leave Lance Stephenson in the corner, leaving West wide open for a jumper at the top of the key.
Here the Mavericks' Gal Mekel is again attacking that pocket of space, forcing the defender to retreat and creating space for Samuel Dalembert to roll down the lane.
As Dalembert rolls down the lane, Lillard is forced to rotate down onto Dalembert which leaves Monta Ellis all alone behind the three-point line.
The Trail Blazers' system for defending the pick-and-roll is sound, and they have the kind of long, mobile big men to make it work. The problem is it takes a near perfect mix of aggressiveness, awareness and communication to pull it off.
Five defenders are simply not enough to completely remove the empty space from a basketball court. But there is a razor thin margin of execution between forcing an offense into the spaces you want them to operate in and allowing the offense to manipulate that space and how it is used.
Right now the Blazers are finding themselves on the back end of that spectrum.
Statistical support for this story from NBA.com/stats