Celtics' amazing start: Can they keep it up and contend for a championship?

From ESPN - November 14, 2017

Since losing their first two games in the 24 hours after seeing All-Star newcomer Gordon Hayward suffer a horrific ankle dislocation and fractured tibia on opening night, the Boston Celtics have ripped off 12 consecutive wins to hold the NBA's best record at 12-2.

Despite more bad luck in terms of injuries with stars Al Horford (concussion) and Kyrie Irving (facial fracture) missing time, Boston has relied on the league's best defense and a series of timely comebacks to keep on winning.

While the 70-win season the Celtics are currently on pace for is not realistic, can they sustain enough of their hot start to remain championship contenders without Hayward?

How Boston is winning

Without Hayward, and particularly without either Horford or Irving on top of that, the Celtics have been below-average offensively. They rank 18th in offensive rating, and even that has been bolstered by frequent second-chance scores and efficiency in transition. According to, Boston's half-court offense ranks 23rd in terms of points per play. Of the seven teams averaging fewer points per play in the half court, only the Denver Nuggets are .500 or better.

The Celtics' fast start, then, has been built almost entirely at the defensive end. Boston's league-leading 95.4 points allowed per 100 possessions is 3.1 points per 100 better than the next-best team in defensive rating (the Oklahoma City Thunder) and 8.4 percent better than league average (104.1 points per 100 possessions). If the Celtics were able to maintain that, it would surpass their 2007-08 championship team as the second-best defense relative to league average since the ABA-NBA merger.

Of course, the odds are Boston wo not continue to play this well defensively. There are plenty of examples of teams starting a season at historic levels only to regress to the mean. And the Celtics' reliance on holding opponents to low shooting percentages makes them particularly vulnerable.

Will opponents keep missing shots?

As Ben Falk investigated on last month, opponent shooting percentages early in the season tend to be less predictive than shot distribution, which has not been a real strength for Boston. If all opponents were making shots at a league-average rate from each of the zones tracked by (in the restricted area, other paint attempts, non-paint 2-pointers, corner 3-pointers and above-the-break 3-pointers), the Celtics' defensive shot distribution would put them 12th in the league in opponent effective field-goal percentage (eFG). They actually lead the league in this category. (Intriguingly, Boston actually had better shot distribution last season, ranking seventh in expected eFG. The Celtics' actual eFG allowed ranked 13th.)

Boston's defense does look more sustainable when we consider how well they have contested opponent shots. Based on Second Spectrum analysis, the Celtics have the best defensive quantified shot quality (qSQ) in the league at 49.9 percent. That measures the eFG we'd expect based not only on the location of shot attempts, but also of nearby defenders (plus shot type), providing more detail. Still, Boston also leads the league in quantified shooter impact (qSI), which is the difference between the expected qSQ and actual eFG (47.7 percent) -- meaning teams are making far fewer shots against the Celtics than we'd expect after accounting for their contests.

Will the Celtics keep winning close games?


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