Friday, December 25, 2015

The Importance of Six-Minute Scoring Spurts in the Warriors’ Winning Streak

Merry Christmas and Happy Holidays!

As part of the NBA's package of Christmas telecasts, the champion Golden State Warriors (27-1) will host Cleveland (19-7) in a rematch of last season's finals. The Warriors have been the big story of the 2015-16 season, starting out 24-0 (a 28-game regular-season winning streak if one includes the last four games of the previous season) to threaten the 1971-72 Los Angeles Lakers' record 33-game winning streak. After a December 12 loss at Milwaukee to end the streak, Golden State has won three in a row.

On this holiday occasion, I'd like to look back on the Warriors' winning streak, using an unusual lens. Offense is the team's forte, as seen in the NBA team-scoring rankings. Some basketball analysts look at statistics such as teams’ points per game or points per 100 possessions. To understand the Golden State Warriors’ success over the past season and a half, in my view, we have to look at smaller segments of play. Not halves, not quarters, but six-minute “eighths” of games. When the first-quarter clock runs down from 12:00 to 6:01, that would be the first eighth; from 6:00 to 0:00, the second. The eighth and final eighth would run from 6:00 to 0:00 of the fourth quarter.

In the 2015 playoffs, the Warriors played 21 games and thus 168 eighths of basketball (overtimes are not counted within my analyses). In 22 of these 168 eighths (13%), Golden State scored 18 or more points, which translates into 3 or more points per minute. If a team maintained a 3-points/minute pace for a full 48-minute game, it would score 144 points. Thus, I use 18+ point eighths as a marker of offensive explosiveness. The 22 eighths in which the Dubs scored 18+ points during these playoffs included three of 24 points (4 points per minute) and one of 25 points.

Through the Warriors’ first 25 games of the 2015-16 season – 24 wins followed by a loss – they have recorded 46 eighths of 18+ points in the 200 eighths they’ve played (23%). (Given that opposition is stronger in the playoffs than in the regular season, it’s not surprising that Golden State’s percentage of eighths with 18+ points is higher in the latter.)

The Warriors’ best eighth of the current season, as far as I can tell, occurred in the last six minutes of the first quarter on December 8 at Indiana. After scoring 17 points in the first 6:00 of the quarter, the Dubs added 27 points in the latter half of the first quarter (the second eighth of the game). This explosion included four treys (plus Klay Thompson making all three free throws after being fouled behind the arc).

After the Warriors’ 114-98 win at Brooklyn to go 22-0, acting coach Luke Walton was quoted as saying that, "It's one of our biggest strengths, is that we're never out of a game and we're always one little run away from putting a game away."

The following graph plots Golden State's points scored in the final 6:00 (the eighth eighth) of their first 25 games this season, as a function the number of points by which they were leading or trailing with 6:00 minutes left in regulation, We see that the Warriors’ greatest scoring outbursts in the final eighth have occurred when they have trailed or been tied heading into them. (For those with some statistical training, the correlation between Warriors’ margin entering the final eighth and their points scored in the final eighth is r = -.52, p < .01.)

In some ways, this finding is totally intuitive. Trailing or being tied should motivate a team (especially one, such as the Warriors, who were trying to maintain a long winning streak) to play extra hard; conversely, when a team is way ahead, it likely will put reserves in the game and run time off the clock, both resulting in lower offensive output. In another way, however, the finding is not so intuitive. If you’re trailing or tied late in the game, it could mean you are playing a tough opponent and/or having an off-night, which are not conducive to big scoring runs.

The above graph also shows that failure to respond as expected is what put the Warriors’ winning streak in jeopardy in Game 24 at Boston (a double-overtime Golden State win) and helped end it the next night in Milwaukee. According to the trend-line projection, the Dubs would have been expected to score 17 or 18 points in the final eighth of the Celtics game, but instead scored only 12 (this discrepancy is depicted by the red dashed vertical line). Trailing by 13 at Milwaukee, Golden State would have been expected to put up 20 in the final six minutes, but instead scored only 15.* Given that the Boston and Milwaukee games were the sixth and seventh of a seven-game road trip, the late-game loss of the Warriors’ explosiveness doesn’t seem surprising.

I don’t expect media outlets to replace the standard quarter-based line-score with one organized by eighths. For highly explosive teams such as the Warriors, however, I do believe eighths are a useful lens for statistical analysis.


 *The Warriors lost to Milwaukee by 13 (108-95), so strictly speaking, even if Golden State had scored the extra five points predicted by the correlational analysis, it still would have lost. Had the Warriors shown more offensive prowess in the final 6:00, however, the Bucks might have begun to feel pressure and perhaps the ending would have unfolded differently.

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