Forsberg: Celtics Must Rekindle Defensive Brilliance That Led Last Year's NBA Finals Run

Forsberg: C's must rekindle defensive brilliance that led last year's Finals run originally appeared on NBC Sports Boston

So much of the angst over the Boston Celtics’ recent tailspin has focused on the team’s offensive woes. Jayson Tatum has slumped out of the All-Star break, Marcus Smart's assist percentage has plummeted since returning from an ankle injury, and Boston’s success has hinged heavily on 3-point shot making.

But this isn’t a new problem. The Celtics, since starting the year on a historic offensive pace, have been a middling bunch. Since a December 10 visit to Golden State -- a 40-game stretch that offers a half season worth of data -- Boston ranks 18th in the NBA in both offensive efficiency (114.3) and true shooting percentage (58.2).

Boston’s ability to win ugly for much of that stretch helped mask their dive in offensive efficiency. The team still has plenty of stretches where it rekindles some of that early-season magic, it simply has not worked hard enough to maintain it.

Mannix: Celtics need to get back to defensive identity

Those scoring lulls have simply been accentuated as the team has blown a trio of double-digit leads in its past three games, fumbling away 57 points worth of leads while falling to the Nets, Knicks, and Cavaliers in brutal fashion.

But the real story here isn’t Mazzullaball, or living and dying by the 3. The Celtics were constructed to be a 3-point heavy team and some variance in the nightly output should be expected.

The bigger issue with Boston’s recent play is the dip in defensive efficiency. If the Celtics are going to replicate their postseason run of a year ago, the focus needs to be on living and dying with defense.

Boston’s defense has been solid for much of the season and slots 4th in the NBA while allowing 111.2 points per 100 possessions. The Celtics’ offense was humming at such a high level early in the year that the team didn’t need to be as laser focused as it was at the end of last season.

Now, as the team’s offense varies from quarter to quarter, the Celtics need a more consistent defense. Even before this recent rough patch, Boston’s defense was slipping. Boston’s defensive rating is at 114.9 since February 10, ranking 16th in the NBA. Since the All-Star break, that number is up at 116.1 and ranks 18th.

So why the regression on that end? The Celtics got their preferred starting five in place coming out of the All-Star break but that group struggled to rekindle last year’s magic. Robert Williams missing time hasn’t helped, while Smart hasn’t been quite himself on either end since the ankle injury. Teams haven’t been afraid to go at 36-year-old Al Horford, even if he’s repeatedly shown he can crank it up when the games matter most.

Most notably, Boston’s defense just hasn’t been up to snuff in critical moments. For the season, the Celtics rank seventh in the NBA in clutch-time defensive rating, holding teams to 104.8 points per 100 possessions in the final five minutes with the score within five points. In five crunch-time games since the All-Star break, Boston has a defensive rating of 117.1. And somehow they still won three of those games (mostly because of Jayson Tatum’s heroics).

So stomp your feet all you want about 3-pointers but if the Celtics could have stopped Immanuel Quickley or Donovan Mitchell at all in the final minutes of their last two games, they win despite all their scoring lulls.

The good news for Boston, if it can get back healthy for the postseason, is that the familiar double-big pairing of Horford and Williams III has posted a 103.3 defensive rating in 297 minutes together. There are bumps to smooth out with that starting group but its’ a good sign that Boston’s two primary bigs have thrived together when healthy.

Derrick White running with the Williams III-less starters has a 106.8 defensive rating in a team-high 301 minutes together. There’s a chance to tap into the success of that group starting with Wednesday’s visit from the Blazers while Williams III works his way back from a hamstring injury.

The Celtics need to tighten up on both ends to be a legitimate title contender. But given the nature of playoff basketball, it would really aid them to get their defense back on a level closer to what we saw last season.