Celtics’ offense could be one for the books

Paul Pierce and Ray Allen are both shooting better than 50 percent from the field for the first time in their careers. (Elsa/Getty Images)

Fifty-six teams have finished an NBA season with a field-goal percentage of 50 or better, according to Basketball-Reference. Of those 56 clubs, 41 played in the decade starting with the 1977-78 season and ending in 1986-87, when it was typical for at least two teams to hit the 50 percent mark every season.

Since the end of the 1980s, only nine teams have pulled the trick. Since 1996-97, only two teams have done it — the Suns in both the 2007-08 and 2008-09 seasons.

So the Celtics, shooting 50.2 percent after blitzing the Lakers on Sunday, are on pace to do something rare. I’ve written before about the unusual nature of Boston’s offense, which features few offensive rebounds, free throws or three-pointers — and gobs of turnovers. Boston is almost completely reliant on hitting the first two-point shot it takes on any possession.

Another way to put Boston’s weird year into perspective is to compare the Celtics to other recent teams that shot at least 50 percent. All numbers below are from Basketball-Reference, and the last number, in bold, is where the team ranked in offensive efficiency (points per possession) during that particular season.

• 2010-11 Celtics: 50.2 percent shooting (1st); 108.3 points scored per 100 possessions (11th)

• 2008-09 Suns: 50.4 percent shooting (1st); 113.6 points scored per 100 possessions (2nd)

• 2007-08 Suns: 50.0 percent shooting (1st); 113.3 points scored per 100 possessions (2nd)

• 1996-97 Jazz: 50.4 percent shooting (1st); 113.6 points scored per 100 possessions (2nd)

• 1994-95 Jazz: 51.2 percent shooting (1st); 114.3 points scored per 100 possessions (4th)

• 1994-95 Magic: 50.2 percent shooting (2nd); 115.1 points scored per 100 possessions (1st)

• 1991-92 Bulls: 50.8 percent shooting (1st); 115.5 points scored per 100 possessions (1st)

• 1991-92 Warriors: 50.7 percent shooting (2nd); 113.6 points scored per 100 possessions (3rd)

• 1990-91 Celtics: 51.2 percent shooting (1st); 112.6 points scored per 100 possessions (3rd)

• 1990-91 Bulls: 51.0 percent shooting (2nd); 114.6 points scored per 100 possessions (1st).

We’re obviously cutting across different eras with different sets of rules, but the trend is clear: Teams that have shot 50 percent over a full season since doing so became extremely unusual have invariably ranked among the league’s top four offenses in terms of points per possession. The Celtics currently rank 11th. And they’re not really close to the top five, either.

This is not a knock on Boston, which has a creative playbook, an all-world point guard and some super-efficient shooters. And it’s also worth nothing that during last year’s playoffs — when the Celtics got healthy and started to care — Boston got to the line more often, cut its turnover rate and improved its offensive rebounding rate. In other words, the current Celtics likely have another gear, and that gear may lead to a more diverse offense.

And even so, a top-10 level offense is a big improvement from last year’s regular-season mark, and it’s good enough to win the title when combined with Boston’s top-notch defense.

But take a minute to digest and appreciate what a strange season Boston is having on offense.