Defending the 3: How the Celtics are losing the battle behind the arc

The influence of the three-pointer on today’s NBA can hardly be overstated. More teams and players are relying on the three-pointer than ever before, and many offenses generate points in bunches through the advantages that can be derived from having strong perimeter shooters. That means both making and defending shots from behind the arc has become a must for successful NBA teams, and this vital interplay is something the Celtics have been inconsistent with throughout the season. In fact, during their recent struggles, the Celtics have had little success with this crucial battle on the perimeter, often falling prey to teams who are far superior from the three-point line.

One of the team’s biggest issues over the past month or so has been the diminished performance of its defense. Much of this has to do with the quality of Boston’s opponents (the Thunder, Warriors, Trailblazers, and Rockets are all among the best offenses in the NBA), but even so, what was a strength for the Celtics in the early going has recently been anything but.

The C’s still rank within the top half of NBA defenses in terms of points allowed per game (98.7), and over the course of the season, they have defended the three-point line especially well. Through the squad’s first 40 games, the Celtics have held opponents to just 34.6% shooting from behind the arc, good for eighth-best in the league. Indeed, defending the three, and forcing opponents into long mid-range jumpers has allowed the Celtics to succeed on the defensive end despite no notable defensive stoppers or rim protectors populating the team’s roster.

But over their last 14 games, in which the Celtics have gone 2-12, they have struggled mightily on defense, allowing 104.1 points per contest. The team’s decline in three-point defense has been even more alarming, with Boston’s opponents shooting 38.0% on three-pointers dating back to their December 18th loss against the Pistons. That may not seem like a drastic drop-off in performance, but such a mark would rank third-worst among all NBA squads if carried out through the season so far.

The issue only grows when you also consider the Celtics’ subpar perimeter shooting on the offensive end. Boston has made just 33.5% of its three-point attempts this season (27th in the NBA), and that figure has dropped to 29.2% over the last 14 games. As it stands, the Celtics have only two players, Jeff Green and Avery Bradley, who are above-average three-point shooters.

Each night, then, the C’s are giving away points to their opponents just due to their struggles from the perimeter. During their recent 2-12 stretch, for instance, the Celtics have made 39 less threes than their opponents, which roughly translates to 8.5 points per night. Put another way, the Celtics have made more than seven three-pointers just twice over their last 14 games. On the other hand, their opponents have done so on 11 different occasions throughout that stretch.

This isn’t some unsolvable problem that threatens to plague the Celtics for multiple seasons, of course. Danny Ainge is well aware of the team’s deficiencies, and more importantly, realized the roster had some pretty glaring weaknesses coming into the season. Such issues are instead a product of the rebuilding phase the Celtics are now going through. Given the franchise’s focus on playing smart, efficient basketball, I wouldn’t expect the Celtics to suffer from such obvious shortcomings for much longer.

Soon (perhaps even by next season if the trades keep coming) the squad will be in a better position to benefit from the advantages that three-pointers can provide. The Celtics have shown the ability to defend the perimeter well at times (at least when not playing against the top-tier teams). And when Ainge adds some shooters to the roster, the C’s will start winning the battle behind the arc, and hopefully some more games in the process.

Alex Skillin is a regular contributor to CelticsBlog. He writes, mostly about baseball and basketball, at a few other places across the Internet. You can follow him on Twitter at @AlexSkillin.