This week’s issue of Sports Illustrated has a rather interesting excerpt on home court/home field advantage from the soon-to-be-released book “Scorecasting: The Hidden Influences Behind How Sports Are Played and Games Are Won,” by Tobias J. Moskowitz and L. Jon Wertheim.
The authors take a numbers-based look at what actually creates the advantage at home across most of the major sports worldwide at the professional and, sometimes, the collegiate level. The findings are interesting not only because of the apparent limited scope of home field/court advantage, but also because of the astounding level of consistency that teams in a particular sport enjoy the benefits of home.
First of all, the authors’ study found what everyone already knows: The home team has an advantage. But how much of an advantage the home team has varies by the sport itself more than any other factor. For example, the authors’ numbers indicate that home field advantage is the most significant in soccer. The win percentage of home teams in three of the most popular leagues in Europe, including the English Premier League, is about 65 percent. And in 40 other leagues in 24 other countries, it’s about 63 percent. Amazing. And NFL teams (57.6 percent) win at about the same rate at home as Arena Football League teams (56 percent) and college football teams (57 percent) — at least when only conference games are considered in college to account for the propensity by power teams to schedule weaklings in the non-conference schedule.
The “Scorecasting” numbers also bust a number of go-to explanations for how the home court/field provides an advantage. One is that the home court boosts the performance of the players themselves at home. To cite an example used in the excerpt, in 23,000 NBA games studied, free throw percentage of home teams was 75.9 percent — the exact same percentage shot by visiting teams. So apparently there’s no use in wiggling little balloons or whatever behind the basket. The authors’ study also shows that travel itself doesn’t affect teams that much either (for example, a road team is equally as likely to lose in a nearby away game than a faraway road game), nor do unique home characteristics like the ways in which baseball parks differ (hitters’ park teams perform just as well as pitchers’ park teams on the road in a third “control” park, as in the Rockies and Mets both win and lose as the numbers predict any road team would when playing in St. Louis).
One of the four myths debunked in the authors’ work, that home-cooked scheduling benefits help teams win, is less true in the NBA than in other sports because of the NBA’s back-to-backs, which are relatively unique across major worldwide sports. NBA teams often play both ends of back-t0-backs on the road, and never play both at home. NBA teams play an average of 14 out of 20 games in back-to-backs on the road, and win only slightly more than a third of the 14 road games, which is lower than their total win percentage away from home. The authors assert that this counts for 21 percent of home court advantage in the NBA, although at least in the Sports Illustrated excerpt they don’t explain how they arrived at that number. [quote]
So what actually does make being home an advantage in sports? Officiating. Officials are more likely to side with the home team in every sport on certain calls, according to the “Scorecasting” numbers. In baseball, balls-and-strikes calls tilt in favor of the home team. In soccer, referees added on more time at the end of close games (stoppage time, the determined-on-the-fly amount of time added to a half to account for injuries and other stoppages of play because the clock in soccer never stops) in which the home team trailed and less in close games in which the home team led. Home teams in football receive fewer penalties than away teams. And in the NBA (and other sports), the size of the home crowd tends to affect how the games are called. Traveling is called 15 percent less often against players in home whites, but the number jumps to 28 percent when the arena is packed. Lightly attended games lead to wins for the home team 55 percent of the time in the NBA, and the most attended games are won by the home team in 69 percent of games.
(Interestingly, the home field advantage in soccer melts away in games when the home team is forced to play in an empty stadium. Sometimes teams in foreign leagues are forced to play with no fans as punishment after instances of rioting or hooliganism. And the authors’ point to a study when soccer referees are made to watch tackles on video with the volume turned off while another group watches with the volume turned on, and crowd noise had an undeniable affect not only on how the referees called or didn’t call a foul, but also on the level of anxiety they reported feeling when making the call.)
No naturally, about 800 words into this column, it’s time to steer it back to the Thunder and look to see how the numbers are bearing out so far this season in Oklahoma City. The raw numbers show OKC is better at home than on the road, with a 15-6 record in the still-the-Ford Center against a 12-7 record outside of the Sooner State. This jives with the trend across the rest of the league so far, with every team except Dallas winning at a better clip at home than on the road.
The back-to-backs haven’t exactly been kind to the Thunder, but they haven’t been murderous either. OKC’s .400 losing percentage on the road in either game of a back-to-back fares slightly worse than the league-wide percentage offered in “Scorecasting,” but the overall 9-5 record in back-to-backs, .642, is only slightly below the Thunder’s overall winning percentage of .675 through 40 games. Only four of the Thunder’s 14 games that are part of a back-to-back have been at home, and that number will hold true the rest of the season with only four of 14 remaining halves of back-to-backs at home as well. So maybe that has affected Oklahoma City the most as far as home court advantage this season.
Fouls called is the best way I could come up with to track the influence of officiating on the Thunder this year. I realize this is an imperfect stat, especially in basketball when teams need to foul when trailing late in close games, but it’s basically all I have to go on. I couldn’t find a stat website or other convenient source that tracked traveling calls like “Scorecasting” does, so I have to stick with fouls for now.
Much to what I assume would be David Stern’s delight, the numbers show basically no preference for the home team across Oklahoma City’s 40 games so far this season. In 21 home games, officials have whistled 463 fouls against the Thunder and 476 against visitors, or 22 fouls per contest against OKC and 22.6 against the road team. In 19 road games, officials have called 420 fouls on the Thunder and 420 fouls on the home team, or 22.1 fouls per game per team.
That surprises me just a little bit considering the packed houses in front of which the Thunder typically plays, especially at home. According to the “Scorecasting” numbers, that should tip the balance even more toward OKC than playing in front of New Jersey-type crowds would. Oklahoma City plays at home in front of an average crowd of 99.6 percent of capacity, good for 10th in the league by that measure. And the Thunder is tied for sixth in the league as a road draw, with opposing arenas averaging 91.7 percent of capacity when OKC is in town. You would think that the referees would favor the home team at least a little more often with that high of a league ranking as a road draw.
(Quick aside: How dumb is it that some teams insist on listing attendance for some games at more than 100 percent? The Mavs claim to have crowds of 103.8 percent of capacity on average. That violates the very definition of the term “capacity.”)
So have NBA referees just been that good, meaning unswayed by home crowds, through the Thunder’s 40 games this season, or are we just dealing with an imperfect stat and a small sample size? Who knows. The research used in “Scorecasting” is so exhaustive that I’m sure it has more to do with the imperfect stat and sample size than anything else. Although anecdotal evidence gleaned by my admittedly slightly biased eye — James Harden’s leg swing foul and Serge Ibaka’s final foul on Thursday night, anyone? — would indicate the Thunder is getting screwed a little bit at home.
But it’s worth noting that “Scorecasting” says what psychologists call conformity, social influence having an effect on people’s behavior and decisions, is what leads to officials’ favoritism of the home crowd. “When humans are under enormous stress — say, making a crucial call with a rabid crowd yelling a few feet away — it is natural for them to want to alleviate it,” as the authors state. “In that case (referees) aren’t consciously favoring the home team; they are doing what they believe is right. In trying to make the right call, they conform to a larger group’s opinion, swayed by thousands of people witnessing the exact same play they did.”
The lesson then, in my mind, isn’t that Thunder fans should yell louder on defense or do more to exhort the home team on the offensive end, but focus more on influencing the refereeing. Boo like crazy when we think they screw up, and applaud like mad when we think they do well. It turns out that may be the only way, supported by statistics, that the crowd in Oklahoma City or any other can truly influence the game.