A Half Baked Predictive Look at the 2010 NBA Playoffs

Posted on 09/02/2010 by

15



So I read a good piece today on the Sports Skeptic blog (see here) that took a look at my half baked notion about the difference between the regular season and the NBA playoffs (see here).  The key question of the piece is this:

Would you rather have a top-heavy team or a deep team?

The author does an interesting job of answering that (go read it) . The article and the question  inspired me to take a deeper look at the 2010 playoffs thru the lens of the Half Baked Theory. Will looking at the Top six for each team and ranking teams based on this match up with what we saw play out in the playoffs.

The Half-Baked Primer

To review , the half baked notion is that what wins in the regular season is not necessarily what  gets you the trophy. Where you need depth (you top 10) to win in the regular season in the playoffs your top 6 is what matters. For the regular season,  using all the data from every season since the merger, the data looks like this :

For the playoffs,  using all the data from every season since the merger, the data looks like this :

So we can conclude:

  • Your starting five account for 82% percent of your wins in the regular season.
  • Your second unit is important over the course of an 82 game regular season accounting for 18% of your wins
  • After that everybody else is statistically meaningless.
  • The best two players accounted for 56% of a teams wins in the Playoffs.
  • The top three players are just below the pareto threshold
  • The next three (4,5,6th man) account for the rest of the positive win contribution about equally.
  • After that everybody else actually hurt teams in the playoffs.

So you need a good 1-10 in the regular season but the better your top six the more successful you are going to be in the playoffs. So how does the theory match up against reality?

Ranking Teams for 2010

Let’s look at the data from the 2010 regular season. I’m going to look at the following data :

  • Total Possessions per game = (FGA + TO – Oreb + (FTA*.44) )*2 divided by total minutes divided by 48
  • Minutes played, Wins Produced for:
    • All the players
    • The Top 10 by minutes played during the regular season
    • The Top 6 by minutes played during the regular season (who we thought they’d be in the playoffs)
    • The Actual Top 6 by minutes played during the playoffs (who they were in the playoffs)
  • I then calculated the average WP48 per player and then and adjusted version for pace using possesions (under the assumption that pace is important for head to head matchups).
  • I then ranked the teams based on their adjusted WP48 for:
    • All the players
    • The Top 10 by minutes played during the regular season
    • The Top 6 by minutes played during the regular season (who we thought they’d be in the playoffs)
    • The Actual Top 6 by minutes played during the playoffs (who they were in the playoffs)
  • I then ran simulations based on the adjusted WP48 for the playoff top 6, the marginal home court advantage ( about .606 over the last ten years) and a seven game series.

The Tables looks like this:

Click it. You know you want to.

The Tables reveal the power of the Half Baked Notion. Orlando was the best regular season team but based on the guys they played in the playoffs were only 4th best. Cleveland I’ve covered extensively before ( here and here) but at the end of the day they lost to a good Boston team (which by the numbers was the only team with a puncher’s chance at beating them before they self destructed).  The surprising Celtics are revealed to not be that surprising after all. The Champion Lakers were only 3rd best but they (by virtue of having homecourt) were predicted to win around 45% of the time.

All in all, I’m pretty happy with the results ( which by the way are top heavy all the way).

Science!!! (courtesy of xkcd.com)

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