Gelf Magazine - Looking over the overlooked

Sports

March 26, 2005

Sharing the Love

Illinois guards deserve their unselfish reputation. But will passing the rock bring them a national title?

Carl Bialik

In Illinois's Sweet Sixteen victory over Wisconsin-Milwaukee, the nation's No. 1 team demonstrated its most aesthetically pleasing qualities. The three starting Illini guards—Dee Brown, Luther Head, and Deron Williams—dished the ball around the perimeter and into the post, combining to shoot 20 for 39 from the field, 9 for 18 from three-point range, and rack up 16 assists.

Sure, it's pretty when stars create their own baskets. Over the long run, though, I'd rather watch great tactics than a highlight reel. Like when a team creates shots by moving the ball around and slowly gaining an advantage over defenders until someone gets an open look at the basket and converts.

That got me thinking: How could I quantify that sharing quality? A clue lies in the boxscore of Illinois's latest win: The team had 20 assists on 28 of its field goals, or 71.4%. (FAQFarm.com: "An assist is the principal pass that contributes directly to a field goal, according to the 2005 edition of the NCAA Basketball Statisticians' Manual.") That struck me as a nice way to measure how well the team was passing the ball. So I calculated what the assist percentage for every team in the Sweet Sixteen, using season stats through Thursday. And Illinois was tops, with an assist ratio of 66.3%. The Illini deserve their unselfish reputation.

But just how useful is unselfishness in the task of winning games? Is the team that shares the ball the team that wins the game? It's unclear. Good passing seems to help, but not suffice. The four Sweet Sixteen teams with the highest assist percentages all advanced to the Elite Eight. But the next five lost, the next four won, and the next three lost. (Victors are bolded in the table at bottom.)

I also calculated the correlation coefficient between assist percentage and scoring efficiency for the teams. (I defined scoring efficiency in a previous article; an improvement on field-goal percentage, it measures how well players and teams convert shots into points.) The correlation was 0.593, meaning assist percentage correlated with better scoring, but not to a great degree. Louisville, for instance, has a scoring efficiency equal to Illinois's but is near the bottom of the pack in assist percentage, thanks to the Cardinals' three-point marksmanship.

Further study is needed. A first step would be evaluating assist percentage and scoring efficiency for more Div. I teams, including the other 48 tournament teams and some who missed the cut. Even better: The official statskeepers should count whether the passes that lead to errants shots and those that result in foul shots would have been credited with assists or not. Then we could compare the scoring efficiency on assisted and unassisted shots.

I won't hold my breath for such superstats, though. For now, I'll just enjoy the sweet-passing teams and hope they outlast the less-pretty basketball of their competitors. Join me, and root for a Final Four of Illinois, West Virginia, North Carolina, and Michigan State.

team assist percentage scoring efficiency
Illinois 66.3% 1.168
West Virginia 65.9 1.111
North Carolina 63.8 1.183
Michigan State 62.9 1.181
Utah 61.7 1.189
Oklahoma State 61.0 1.192
N.C. State 60.7 1.122
Washington 59.9 1.139
Texas Tech 59.4 1.110
Louisville 58.6 1.164
Kentucky 57.3 1.082
Wisconsin 57.0 1.066
Arizona 56.4 1.129
Wisconsin-Milwaukee 54.2 1.092
Duke 49.7 1.119
Villanova 48.6 1.073

Carl Bialik

Carl Bialik, a co-founder of Gelf, is a writer for FiveThirtyEight.







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Article by Carl Bialik

Carl Bialik, a co-founder of Gelf, is a writer for FiveThirtyEight.

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