Judging the 3 point shot..........

[ÜberDirk]

The trey is the thing in today's NBA

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By Mark Haubner
ESPN.com


There was something odd the other day while watching a replay of Game 4 of the classic 1981 Eastern Conference Finals series between Boston and Philadelphia.

Namely, the Celtics penetrated into the lane and kicked out to Chris Ford, one of the best outside shooters of the day, behind the 3-point line. With his defender a few feet away and trying to recover, Ford set himself and then … didn't shoot.

It was a slightly jarring moment considering the practices of the contemporary NBA game, where a good look behind the arc is rarely passed up and plenty of bad looks get hoisted up as well.

And it served to underscore that the real revolution in the way the game is played did not occur when the 3-point line was introduced for the 1979-80 season so much as in the last eight seasons or so, when the use of the trifecta has truly proliferated.

The comparative numbers are striking: In the 1980-81 season cited above, the Celtics went 65-241 (.270) behind the arc as a team. In 2001-2002, Antoine Walker went 222-645 (.344) on threes all by himself.

Despite shooting fewer than three treys a game -- and making less than one per -- Boston ranked third in the league in both makes and attempts in 1980-81. The Hawks, meanwhile, shot just one trifecta per game, and made only 10 all season!

With all the lamentations about how today's players can't shoot, it's notable that, while maybe the new kids can't knock down the mid-range jumper anymore, they sure can hit the long-range shot much better than the previous generation of players who were around in the 3-pointer's early days.

In 1980-81, the San Diego Clippers -- paced by the trio of the immortal Freeman Williams, current USC head coach Henry Bibby and current SlamBall head coach Brian Taylor -- led the league with a .324 3-point percentage, a number far below the 2001-02 league average of .354, which would have left them ranked 27th last season. And the Clips were the only team to so much as break .300 that season; the league percentage as a whole was a pathetic .245.

Similarly, Chris Ford's 3-point percentage of .330 was good for seventh place in '80-81. Last season, it would have put him down near Eddie Griffin in 73rd place.

Here is a further breakdown of the state of the longball, circa 1981 vs. today:

'80-81 '01-02
Most made, team 132, San Diego 699, Boston
Most attempts, team 407, San Diego 1946, Boston
Fewest made, team 10, Atlanta 214, Philadelphia
Fewest attempts, team 82, Atlanta 745, Philadelphia
Average made-att., per game 0.5 - 2.0 5.3 - 14.7
Best %, team .324, San Diego .388, Washington
Worst %, team .122, Atlanta .299, Philadelphia
Overall %, league .245 .354
Most made, player Mike Bratz, Cle. 57 Ray Allen, Mil. 229
Most attempts, player Mike Bratz, Cle. 169 Antoine Walker, Bos. 645
Best 3-point FG%, player Brian Taylor, SD .383 Steve Smith, SA .472



When exactly did three become the magic number in the NBA?

There were hints of things to come in the late '80s, when Rick Pitino's Knicks improved from 24 wins to 52 wins over the course of two seasons on a then-revolutionary combination of long-range bombing and pressing D. In 1988-89, New York became the first team to attempt more than 1,000 treys in a season, firing up 1,147 -- over 300 more than anyone else.

Then Pitino took his 3-pointing shooting game back to college, and the 1,100-attempt barrier would not be crossed again until 1993-94, when the Rockets won a championship after shooting 1,285 threes during the regular season. Houston's offensive strategy of isolating Hakeem Olajuwon in the low post and spacing the floor with shooters behind the arc, forcing the defense to either cover the Dream one-on-one or double-team and risk the three, was novel at the time. Now, it's a common M.O.

The tipping point, however, came the following season, when the 3-point line was moved from the distance of 23 feet, nine inches on top (slimming to 22 feet in the corners), to a consistent 22-foot arc all the way around. The impact of the 3-pointer exploded. In 1993-94, teams shot 3.3 for 9.9 (.333) on threes on average. In 1994-95, those numbers shot way up to 5.5 for 15.3 (.359). By 1996-97, the average team performance from downtown climbed even higher to 6.0-for-16.8 (.360).

But perhaps the most important season for establishing the long-term impact of the three was the next year, 1997-98, when the line was moved back to its original distance. The average per-game numbers took a big drop down to 4.4-for-12.4, but those were still up a lot from the '93-94 numbers, the last previous year at that distance. More significantly, the league-wide percentage (.355) stayed surprisingly close to what it had been at the shorter line, much higher than the .333 in '93-94.

NBA League Averages
Year 3PM-A/G 3PT%
'80-81 0.5 -- 2.0 .245
'93-94 3.3 -- 9.9 .333
'94-95* 5.5 -- 15.3 .359
'96-97 6.0 -- 16.8 .360
'97-98^ 4.4 -- 12.4 .355
'00-01 4.8 -- 13.7 .354
'01-02 5.3 -- 14.7 .354
* Line moved from 23'9" on top to 22'
^ Line restored to original distance


At that percentage, why not keep firing? Since then, the averages for makes and attempts have creeped back up towards the '94-95 numbers, while maintaining a consistent percentage. Last season, teams shot 5.3 for 14.7 (.354) in the average game.

Consider further that the average number of total field goals per game has declined over time, and the relative impact of the 3-pointer becomes even more pronounced:


In 1980-81, one in every 44.2 shot attempts was a three.
In 1993-94, one in every 8.5 shot attempts was a three.
In 2001-02, one in every 5.5 shot attempts was a three.

Given the increasing importance that the 3-pointer has had in the NBA, especially since 1994-95, statistical measures haven't kept up. Field-goal percentage has become outdated as a way of evaluating shooting; something that we'll call "adjusted FG percentage" has become more accurate.

Calculating adjusted FG percentage is pretty simple -- basically, you're just trying to give credit for the extra point which is scored when a 3-pointer is made.

The formula is either [FGM + (3PM/2)]/FGA or [(PTS -- FTM)/FGA]/2.

As described at the bottom of our league leader page for adjusted FG percentage:

Adjusted FG percentage measures shooting efficiency by taking into account the total points a player produces through his field goal attempts. For example, if Shaquille O'Neal was 3-for-5 on field goals, all two-point shots for six points, then his adjusted field-goal percentage is .600 (i.e., FG% = [(6/5)]/2 = .600). Meanwhile, if Ray Allen is 2-of-5 from the field, but his two made field goals are both 3-pointers for six points, then his adjusted FG percentage is .600 (i.e., [(6/5)]/2 = .600).

As more and more threes are made around the league, the impact of adjusted FG percentage in illuminating true shooting efficiency becomes heightened. For example, back in 1980-81, when just 0.5 threes were made per team per game, the overall league FG percentage was .486 and overall adjusted FG percentage was .489, so the stat's impact was negligible. However, last season the overall league FG percentage was just .445, but overall adjusted FG percentage was a respectable .477, and there are real stories to tell in terms of the teams and players that best bridged that gap.

In evaluating last year's individual Adjusted FG% league leaders, the number which is initially most striking is Brent Barry's .611, which easily led the league. (And, amazingly, when looking at all players, rather than just those with enough FGM to qualify, Barry's brother Jon is right behind him at .604.)

What's even more startling, though, is that Shaquille O'Neal could wind up second (.579) in a stat which is seemingly most rewarding to players who can hit the deep ball accurately and often, yet the big guy went just 0-for-1 on 3-pointers all season. He's just a remarkably efficient player.

In looking at teams, let's take the two Atlantic Division teams at the extremes: Boston, which made more threes than anyone else, and Philadelphia, which shot woefully from downtown, finishing last in makes, attempts and percentage.

In standard field-goal percentage, Philadelphia ranked 22nd at .436 while Boston was dead last at .424.

But, in looking at Adjusted FG percentage, the Celtics jump up to 15th at .476, while the Sixers fade to 28th at .452.

Which is more accurate? Depends. How often was Philly's offense just painful to watch last year, as they scrounged through dry spells? And, how often did the C's bust out of a seemingly tough stretch with a quick flurry of threes?

It's not complicated, people. Don't be afraid, it's not weird or sabermetric. Adjusted FG percentage simply evaluates how many points are scored from field-goal attempts, and in basketball, it doesn't get much more elemental than that.

Mark Haubner, a former lead editor of NBA.com, is a producer at ESPN.com.

[LRB]

UD: Great article. It certainly gives a perspective on the 3 that I hadn't thought about. The adjusted FG% comparison showing that todays average is much closer to the average 20 years ago than I 1st thought. It appears that the 3pt shot is not directly responsible for the leagues scoring woes at least from a % made basis. But I wonder if when you take into account the fewer fouls that are drawn on 3's versus closer shots if if might be. I don't have any valid numbers to prove or disprove this. Would be very interested to see if anyone might though.

[ÜberDirk]

"But I wonder if when you take into account the fewer fouls that are drawn on 3's versus closer shots if if might be."

Good question.

[Drbio]

UD- nice article. Thanks.

[OutletPass]

Quality Post shows what UD is capable of when he takes his meds...I know he disturbs most everyone and got another "timeout" for it...but this IS a quality post...wish I would have thought of it.

Adjusted Fg% IS a better measure...but I STILL have a hard time watching the CELTS...I just hate the "volume" 3 pt shooting...it takes away from the overall game IMO.

The Mavs use the 3 very well...not their main game and not a useless weapon. Just another trick in their arsenal. And I do think that they'll start dropping them again soon...the deviation from the norm is a little bit much right now.