# Boston versus the field

Since the NBA playoffs are starting today, I figured I’d throw out my own predictions. I used something I call “True Winning Percentage” (which I will explain some other time, but essentially, it takes into account opponent’s records, and opponents’ opponents’ records, and opponents’ opponents’ opponents’ records, and so on, and determines what a team’s “true” winning percentage would be if they played each other team infinite times, at least, theoretically), to calculate odds for each first round matchup, and then compared those projected winners and so on. Here are my predictions, along with my estimated probabilities of each team I pick to win actually winning the series:

 Likely victor Probability of likely victor winning series BOS>ATL 0.8509 CLE>WAS 0.5313 ORL>TOR 0.6414 DET>PHI 0.7266 LAL>DEN 0.6114 HOU>UTA 0.543 SAN>PHO 0.5303 NOR>DAL 0.5753 BOS>CLE 0.7829 DET>ORL 0.5894 LAL>HOU 0.5257 SAN>NOR 0.513 BOS>DET 0.6384 SAN>LAL 0.5004 BOS>SAN 0.6198

Note that the matchup between San Antonio and LA is essentially a dead heat. However, Boston has essentially identical odds against both, so the final outcome is not so much in doubt.

I also calculated overall odds of each playoff team winning the title, given their probability of winning against each other playoff team, these odds are as follows:

 Team True Win% Prob of championship bos 0.8106 0.7753 sa 0.7242 0.0496 lal 0.7239 0.0491 no 0.7137 0.0352 det 0.708 0.0292 hou 0.7029 0.0247 pho 0.6993 0.0219 uta 0.6657 0.0071 dal 0.6479 0.0039 orl 0.6281 0.002 den 0.625 0.0018 cle 0.5427 9E-05 was 0.5115 3E-05 tor 0.4857 9E-06 phi 0.477 6E-06 atl 0.4285 8E-07

As you can see, Boston has better than 3:1 odds of winning before any basketball has even been played. They are just that much better (even taking into account that they played most of their games against weaker competition) than everyone else. Incidentally, to see the effect of calculating True Win%, notice that Detroit, which had the second best win-loss record, falls to fifth when you take into account their opponents’ (and so on…) success. To conclude, given that the odds of any other team winning come in at 22.47%, I feel pretty safe picking the Celtics this year.

Notice that I don’t predict much success for Utah, contrary to several other prognostications that have them performing very well in the playoffs. I understand that these other folks are using scoring efficiencies and the like, but I’m sticking to my guns. Consider this my bold prediction: Houston will actually beat Utah in the first round (although it will be close).

### 2 responses to “Boston versus the field”

1. Drew

David,

Can you give a little more insight into how you calculated each team’s probability of winning the championship?

The probability of a team winning the championship should be equal to the product of the probabilities of the given team winning each round given the team makes it to that round. Taking your round-by-round win probabilities for the Celtics versus the most likely opponents and adjusting them upward a bit to account for the potential of facing weaker opponents (except for the first round, since the opponent is known) , I get roughly a 35% chance of them winning the championship, which intuitively seems much more reasonable than 78%.

Looking at it another way, the fact that you’re giving Boston a 77.5% chance of winning the title and a 85.1% chance of winning round 1, this implies that the Celtics have a ridiculous 91.1% chance of advancing through the next three rounds given they make it past Atlanta.

I’ve been a fan of your recent analyses (and graphics), but this just doesn’t seem to add up. Is there something that I’m missing?