Thursday, April 17, 2014

Infographic: Fight for the Eastern Conference #1 Seed

All season-long, Indiana set the #1 seed as their objective. While the Pacers completely dominated the first half of the season, they crumbled after the All-Star break (at the same time that Miami and Oklahoma) letting San Antonio capture the overall seed.

But while the overall top seed slipped through their fingers, keeping their grasp on the #1 Eastern conference seed against Miami was a nail-bitting battle till the last few games of the season.

The following infographics show which team had the best winning percentage throughout the regular season. The line is blue when Indiana has the best percentage, red when Miami had it.

Overall season evolution:

Since the All-Star break:

From a 'Ganes Behind' perspective:

Thursday, April 10, 2014

Best of the West or best of the rest?

The NBA finals are right around the corner. Only a handful of games are left to be played in this 2013-2014 season, and homecourt advantage is still a hard fought battle for the top teams.

Miami wants it to increase their odds of winning a third straight championship, Indiana wants it to turn the tables if (more like when) it meets Miami in the Eastern conference finals and avoid a game 7 in Miami like it did last year, San Antonio wants it for the exact same reason except it lost to Miami in game 7 of the finals, and OKC wants it in case it faces Miami in the finals (plus it could provide Kevin Durant with an additional edge on the MVP race against LeBron James).

So yes, everyone wants homecourt advantage, it's been proved over and over again (including in this blog) that there is a definitive advantage to playing 4 games instead of 3 at home in the best-of-7 format. But how key is it really? Does homecourt advantage really determine the NBA champions? Do other factors such as the conference you are in or the adversity faced in the first rounds play a part?

Following on the tradition of the past years, the West is clearly better than the East. Consider this: right now, the Phoenix Suns hold the eighth-best record in the West with 46 wins and 31 losses, and has the last seed for the playoffs. But only two teams have a better record than that in the East, Miami and Indiana. Stressing to hold the last playoff spot in one conference versus a comfortable third seed in the other? Talk about disparity!

But if you had to guess whether the next champ was going to be from the East or West what would you say? That the eastern team would have an easier road to the finals, less games, less fatigue than their western counterpart? Or does evolving in a hyper-competitive bracket strengthen you, in a what-doesn-t-beat-you-makes-you-stronger argument?

Does the overall strength conference have an impact? Does the team with the best regular season record (and hence homecourt advantage) necessarily win? Does the team with the easiest path to the finals have an advantage?

To investigate this I've looked at all championships since 1990 (24 Playoffs) and looked in each case at some key stats for the two teams battling for the Larry O'Brien trophy, among these:
  • number of regular season wins
  • regular season ranking
  • sum of regular season wins for opponents encountered in the Playoffs
  • sum of regular season ranking for opponents encountered in the Playoffs
  • number of games played to reach the Finals
  • sum of regular season wins for all other Playoffs teams in their respective conferences
  • sum of regular season ranking for for all other Playoffs teams in their respective conferences
  • ...

So for Miami in 2013, the data would look something like:
  • 66 regular season wins
  • NBA rank: 1
  • played 16 games before reaching the Finals
  • 132 playoff opponent regular season wins (Indiana: 49, Chicago: 45, Milwaukee: 38)
  • 38.5 playoff opponent regular NBA ranking (Indiana: 8.5, Chicago: 12, Milwaukee: 18)
  • 320 playoff conference regular season wins (Indiana: 49, New York: 54, Chicago: 45, Brooklyn: 49, Atlanta: 44, Milwaukee: 38, Boston: 41)
  • 84.5 playoff opponent regular NBA ranking (Indiana: 8.5, New York: 7, Chicago: 12, Brooklyn: 8.5, Atlanta: 14 Milwaukee: 18, Boston: 16.5)
  • ...
As for the Spurs who were the other 2013 finalists, they had a worse record, emerged from a tougher conference and met stronger opponents while needing surprisingly less games to reach the Finals:
  • 58 regular season wins
  • NBA rank: 3
  • played 14 games before reaching the Finals
  • 148 playoff opponent regular season wins (LA Lakers, Golden State, Memphis)
  • 27.5 playoff opponent regular NBA ranking (LA Lakers, Golden State, Memphis)
  • 366 playoff conference regular season wins (Memphis, Oklahoma, Golden State, Denver, Houston, LA Lakers, LA Clippers)
  • 51 playoff opponent regular NBA ranking (Memphis, Oklahoma, Golden State, Denver, Houston, LA Lakers, LA Clippers)
  • ...

I then ran various models (simple logistic regression, and lasso logistic regression) to see how these different metrics helped predict who would win the champion come the Finals.

The conclusions confirmed our intuition:
  • having more regular season wins that your opponent in the Finals provides a big boost to your chance of winning (namely by securing homecourt advantage, but the exact number of games provided a much better fit than a simple homecourt advantage yes/no variable)
  • there were indications that having a tougher path to reach the finals (more games, tougher opponents) slightly reduced the probability of winning the championship, but none of those effects were very significant

The effect from difference in regular season wins can be seen on the following graph, where we have compared two (almost) identical teams evolving in identical conferences. The only difference between the two teams is the number of wins they've had in the regular season, shown on the x-axis. The y-axis shows the probability of winning the championship.

A five-game differential in wins will translate with a 73% / 27% advantage to the team with the most wins. Only a one-game advantage translates into a 55% / 45% advantage.

The conference effect appears quite minimal, and home-court advantage appears to be key. If Indiana hates itself right now for having let the number 1 seed in the East slip through its fingers, it can always try to comfort itself with the fact that (unless a major San Antonio / Oklahoma / LA Clippers break down occurs over the remaining games of the season), the Western team making it to the Finals would have held homecourt advantage no matter what.

It should also be noted that a "bad" conference isn't synonym of easy opponents. Just look how Brooklyn seems to have the Heat's number this year, the way Golden State had Dallas' in 2007 when it beat the number 1 seed in the first round. All season long the Golden State Warriors were the only ones who could match up against Dallas really well.

UPDATE: as of yesterday, Indiana has reclaimed the top seed in the East, but the final argument can be applied to Miami just as well. Whichever of these teams makes it to the Finals will face a tough opponent.