By Kurt Bullard
There is no denying the importance of home-court advantage in the NBA. During the regular season, we saw the Warriors and Spurs combine to go 79-3 on their home floors. But this is especially true come playoff time—home teams have gone 55-25 in this year’s rendition of the Playoffs. Anecdotally, a down-and-out Toronto team, trailing 2-0 to the Cavaliers and having been written off by most major members of the media, went on to the tie the series by taking two from the Cleveland to the joy of the fans who packed the Air Canada Centre and “Jurassic Park.”
Part of the reason for such a discrepancy in performance has to do with how games are officiated. In games determined by a matter of points, refereeing has the ability to sway the outcome of a game, as was seen in the trainwreck that was the end of Game 2 between the Spurs and Thunder.
I was interested in seeing if a team’s distribution of points from different spots on the floor changed, perhaps as a reaction to more or less aggressive reffing. In this year’s postseason, 52 fouls more have been called against away teams than against home teams. Unfortunately, I do not have access to the data that would tell me where exactly these fouls occurred. My hypothesis was that refs were less likely to award fouls on road players in the paint than they were home players, and that a road team would be more likely to rely on jumpers for scoring than they would driving or posting up.
Using a weighted average so that each playoff team was weighted equally—regardless of games played—squads have scored 8.23 more at home on average than they do on the road, and that 5.61 of this difference is from half-court offense. NBA.com splits up a team’s non-transition points into six categories: catch-and-shoot, pull-up, drives, post-up, paint points, and elbow points. The following is a table of the average difference between home and away points by scoring department. A positive value means that a team scores more points from that play at home than it does on the road. As a reminder, this is only for the postseason – the effects during the regular season may be slightly different.
As you can see, grind-it-out sources of points (driving, posting-up, general paint points) decrease, while pull-up points and catch-and-shoot points actually increase. This is pretty consistent with just looking at post-touch field goal percentage for home and away teams; on average, each team shot 10 percent better at home than on the road after a post-touch.
When it comes to this statistically significant effect—a paired test comparing average driving points for each team yields a p-value of .005—the Cavs have not proven liable thus far in the Playoffs. In fact, the Cavs have scored 2.4 points more driving to the basket on the road than they have in Quicken Loans Arena in its three-and-change series thus far. Both remaining teams also rank in the bottom three in drives per game, as Cleveland and Golden State have relied on three-point shooting to bring them to the Finals.
But it appears that one player on the Cavs might follow the trend and get more driving foul calls at home than on the road—LeBron James. James has drawn a foul once every fifth drive at home, versus on every tenth drive on the road. And, he’s shot just 47 percent on drives on the road, while he’s enjoyed a 70 percent clip at home on the drive.
So while teams tend to rely less on driving on the road, the Cavs and Dubs will most likely rely heavily on shooting, regardless of location. The one question that could dictate the length of this series is how quick the whistle is for LBJ in Oakland versus in Cleveland.
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