Sunday, April 21, 2013

The Point Spread, Home Court Advantage, and the Playoffs

At Wages of Wins, Ed Feng posted recently on the impact of home court advantage in the playoffs.  He found that home court advantage seems to have a bigger impact in the playoffs, even after correcting for relative team strength (e.g. 1 seeds vs. 8 seeds, etc.).

Feng found that home court advantage is worth 4.5 points in the playoffs, compared to 3.2 points in the regular season.  I had noticed a similar phenomena in the Vegas point spreads during last year's playoffs.  When a playoff series would switch venues, I was expecting a 6.5 point swing in the point spread (the betting market values home court at 3.25 points in the regular season).  Instead, the spread was swinging by 7 to 9 points.  For example, in last year's Lakers-Nuggets first round series, the Lakers were favored by 4.5 points in their first two games in LA.  But when the series moved to Denver for game 3, the Nuggets were favored by 4, instead of the expected 2 points.

In this post, I will quantify how much the betting market appears to value home court advantage in the playoffs.  I will also take a deeper look into the stats to see what is driving this home court advantage differential.

Thursday, April 18, 2013

Playoff Seeding Motion Charts - All Teams

Earlier this week, I posted a motion chart showing how the Lakers' playoff seeding probabilities evolved day by day since the All Star break.  The probabilities come from my daily simulations of the remainder of the regular season, added as part of my daily team rankings in February.

With the regular season now finished, I have added all teams, accessible via the dropdown below.  Each bar represents the team's probability, as of that date, of achieving that playoff seed.

The Lakers, Rockets, and Jazz show the most movement in their probabilities, especially for the last couple weeks of the season.  The Heat's chart is interesting in a Zen kind of way.

Saturday, April 13, 2013

Playoff Seeding Probabilities - In Motion

After the All-Star break, I added a new feature to my NBA daily rankings: Playoff Seed Projections.  I used my rankings to simulate the remainder of the season 10,000 times, applied all of the seeding and tiebreaker rules, and summarized the probabilities for each team in a little sparkline-style chart.

Since I archive the projections each day, I can also use Google's Motion Chart API to show how those probabilities have evolved over time.  The Lakers, out of all the NBA teams, have had the most ups and downs in their playoff fortunes since the All Star break.  Click the play button on the chart below to see that in motion (flash-based, not mobile friendly).