Playoff Probabilities

[boooeee]

Thought this might be of interest for people on the board. I've been running daily simulations of the NBA playoffs based on the latest game outcomes and point spreads (my model uses point spreads to generate implied team by team rankings that can then be used to simulate the probability of any hypothetical matchup).

This post has more background, and here are summaries of the actual simulations.

Like I said, I run these daily (10,000 simulations) so not only can you see the latest and greatest probabilities each morning, but you can also see how a team's fortunes have changed over time. It's similar to what Hollinger does here, but it looks like he stopped updating them once the playoffs started.

What's been puzzling me is that the clear favorite ever since I started the simulation (the day before Round 1 started) has been the Spurs. You can see that most clearly on the Birds' Eye view. But if you look at the futures odds being offered by Vegas or the offshore bookies, Miami has been, and still appears to be, the favorite. Any thoughts as to why that may be? Large market bias? The Spurs are too old to sustain a high level of play throughout the playoffs?

The Spurs are guaranteed home court advantage through the rest of the playoffs, correct?

[EvanZ]

Why is that called a "Bird's Eye View"? Is that an area plot when the x-axis is time?

[boooeee]

Why is that called a "Bird's Eye View"? Is that an area plot when the x-axis is time?

Correct. The x axis is the date, and the area is proportional to each team's probability of winning the NBA Finals as of that date. I called it Birds Eye view because it's a vantage point that allows you to visualize the ebb and flow of the probabilities for all teams at once.

If you're a Fringe fan, think of it as the Observers' view.

[EvanZ]

I watched a few episodes of Fringe the first season, but didn't get into it. One of these days I'll get around to it on Netflix though.

[Mike G]

...
What's been puzzling me is that the clear favorite ever since I started the simulation (the day before Round 1 started) has been the Spurs. ..

Spurs were also given best odds by b-r.com
http://www.basketball-reference.com/fri ... f_prob.cgi

[boooeee]

...
What's been puzzling me is that the clear favorite ever since I started the simulation (the day before Round 1 started) has been the Spurs. ..

Spurs were also given best odds by b-r.com
http://www.basketball-reference.com/fri ... f_prob.cgi

Thanks. Didn't realize basketball-reference produced their own simulations as well.

The probabilities were updated this morning, and the Spurs dropped from a 57% chance to win the Finals to a 51% chance. This is due to the fact that the Thunder won their game against the Lakers and that the Heat improved in the rankings. The Heat are a one point favorite against the Pacers tonight, when the prior point spread would have indicated tonight to be a push. The Heat were 6.5 point favorites in Game 2 and home court is worth 3.25 points, so that implied that the Heat were 3.25 points "better" than the Pacers. So, when the series shifted to the Pacers, the 3.25 point home court advantage should have wiped out the Heat's advantage.

I've found that it's the rankings that drive the probabilities a good deal more than the actual game outcomes for a given day. If a team improves in the rankings by a point, that's like going from a 50% chance to win to a 54% chance to win, which can amount to a lot when iterated through all future games.

[Mike G]

Spurs have >50% chance to win the Finals, or to get there?
Even if they have a 2/3 chance to beat Okl (after beating the Clipps) and a 2/3 chance of beating Mia (or whomever), that's only 4/9.

... due to the fact that the Thunder won their game against the Lakers and that the Heat improved in the rankings..

Why do the Heat improve after losing a game, and being without Bosh?
Why does an Okl victory mean they're more of a threat than LA? If the Lakers get hot or improve (MWP returned), doesn't that just mean they may be the stronger possible opponent?

[boooeee]

Spurs have >50% chance to win the Finals, or to get there?
Even if they have a 2/3 chance to beat Okl (after beating the Clipps) and a 2/3 chance of beating Mia (or whomever), that's only 4/9.

It's probability to win, which I agree seems high. According to some quick calcs, the Spurs would have a 70% chance to win if they played the Thunder in the Conf Finals, and about a 65% chance to beat the Heat if they faced them in the Finals, which works out to your 4/9. BUT, the Heat only have a 65% of making the Finals. See the table here.

If the Spurs faced the Pacers, they would have a 90% chance of winning. So, after factoring in the chances that the Spurs could face the Pacers, Celtics, or Sixers in the Finals, their outlook rises to ~50%.

That being said, if you think that Chris Bosh will return for the Heat soon, my simulations are definitely undervaluing the Heat's chances, as the simulations are based on rankings based on the latest point spreads, which currently reflect the absence of Bosh.

[boooeee]

Why do the Heat improve after losing a game, and being without Bosh?
Why does an Okl victory mean they're more of a threat than LA? If the Lakers get hot or improve (MWP returned), doesn't that just mean they may be the stronger possible opponent?

You'll have to ask Vegas about the Heat improvement (my ranking system is based solely on the point spreads and follows them blindly). Interestingly enough, the line appears to have moved to 2.5 points in favor of the Heat. Is Chris Bosh going to play?

[boooeee]

You'll have to ask Vegas about the Heat improvement (my ranking system is based solely on the point spreads and follows them blindly). Interestingly enough, the line appears to have moved to 2.5 points in favor of the Heat. Is Chris Bosh going to play?

Speaking of odd line moves, the Lakers are a 2.5 point favorite at home over the Thunder tonight. That's after being 8 point underdogs in the first two games at Oklahoma. That's a swing of 10.5 points, when you'd only expect a swing of 6.5 points when the series switches venue (3.25 x 2). The Lakers did look impressive against the Thunder in Game 2, but a 4 point difference in relative strength is a lot for one game (especially considering that the Lakers lost). There aren't any key injuries I'm aware of.