Monday, November 29, 2010

Power Rankings and Game Predictions

Power Rankings:

1 - San Antonio
2 - Dallas
3 - Utah
4 - LA Lakers
5 - Orlando
6 - Oklahoma City
7 - Boston
8 - Denver
9 - Chicago
10 - New Orleans
11 - Indiana
12 - Atlanta
13 - Miami
14 - New York
15 - Cleveland
16 - Memphis
17 - Phoenix
18 - Portland
19 - Toronto
20 - Charlotte
21 - Detroit
22 - Houston
23 - New Jersey
24 - Golden State
25 - Washington
26 - Milwaukee
27 - Philadelphia
28 - LA Clippers
29 - Minnesota
30 - Sacramento

*These power rankings are generated using points and wins, and are a direct indication of a team's recent performance.  The rankings are taken from each team's last game rather than after each team's x game.  With that in mind, if you think the rankings are off, please leave a comment.

Predictions for Nov. 30

Boston @ Cleveland - Boston by 7
Detroit @ Orlando - Orlando by 10
Portland @ Philadelphia - Portland by 8
New Jersey @ New York - New York by 2
LA Lakers @ Memphis - LA Lakers by 10
Indiana @ Sacramento - Indiana by 9
San Antonio @ Golden State - San Antonio by 14

Results from Nov. 29

3/4 (75%)

Washington @ Miami - Miami by 8 (Actual:  Miami by 11)
New Orleans @ Oklahoma City - New Orleans by 5  (Actual:  Oklahoma City by 6)
Houston @ Dallas - Dallas by 14 (Actual:  Dallas by 10)
Milwaukee @ Utah - Utah by 10 (Actual:  Utah by 21)

Sunday, November 28, 2010

End-of-Season Projections: 15 Games In

Standing Eastern Conference Wins Western Conference Wins
1 Orlando 53 Dallas 61
2 Boston 53 LA Lakers 61
3 Chicago 49 San Antonio 61
4 Miami 46 New Orleans 57
5 Indiana 45 Utah 51
6 Atlanta 41 Oklahoma City 50
7 Cleveland 36 Denver 47
8 New York 34 Portland 44
9 Toronto 34 Phoenix 40
10 Milwaukee 33 Memphis 37
11 New Jersey 32 Golden State 34
12 Detroit 31 Minnesota 27
13 Charlotte 31 Houston 27
14 Washington 29 Sacramento 27
15 Philadelphia 23 LA Clippers 21

Predictions for Monday:
Washington @ Miami - Miami by 8
New Orleans @ Oklahoma City - New Orleans by 5
Houston @ Dallas - Dallas by 14
Milwaukee @ Utah - Utah by 10

Saturday, November 27, 2010

End-of-Season Projections

Back on November 3rd, while the NBA season was still in its infancy, HangTime blogger, Sekou Smith posted this blog with some end-of-season projections based on average points scored and average points allowed by each team.  At that point in time, no team had played more than three or four games.  Several teams had not yet lost a game while others had not yet won a game.  As you might expect, the results were laughable, projecting three teams would top the 70 win mark with Miami winning a mind-boggling 78.  That means since they had already lost a game, they would have to go almost an entire season while only losing three more.

Whether Smith wanted to get fans riled up or was just entertained by the idea of such preposterous numbers, I knew their had to be a better way to generate projections, even early in the season.

So I got to work.

The formula Smith presents is called the Pythagorean Method, which gives you a ratio based on average points scored raised to x divided by the sum of average points scored raised to x and average points allowed raised to x.

I took this same formula as a starting point and started addressing the issues:

What if a team is having blowout wins and close losses (i.e. Miami Heat)?

I've included a team's actual win percentage in the formula and weighted it to have more and more significance as the season progresses (starts at 50% and increases to 100% by game 82).  If a team like Miami continued their trend until the end of the season, the projection may still say 78 wins, but the standings would tell a different story.  Including this variably weighted factor brings projections closer to reality as more reliable information is collected.

What if a team has a difficult or easy schedule?

I've also included a Strength of Schedule factor that will either bump a team's projection up or down based on the quality of opponents they have recently been playing against.  The Strength of Schedule is calculated by taking an exponential moving average of each opponent's projected win percentage.  I opted to use the projected win percentage over the actual win percentage for all these same reasons.

What if a team starts out undefeated or winless?

 I was a little stumped by what to do with this issue at first.  I thought of carrying over each teams' record from the previous season as a starter, but decided that would cause inaccuracies due to player movements during the off-season (i.e. Cleveland).  I thought about solving that by narrowing the spectrum and limiting it to .400-.600 or so.  That still wouldn't solve problems caused by teams like Cleveland (or more accurately, people like LeBron).  I finally settled on assuming each team was average and project them to finish .500.  This average number is what starts the Strength of Season calculation and allows it to reach realistic calculations early on.

There are other issues that could also be addressed, such as home-court advantage (home team wins approx. 57%) and inter-conference games (west beats east approx. 55%), but I think I've managed to address the most glaring issues.

Here are some end-of-season projections using my current system:

One game in:
Standing Eastern Conference Wins Western Conference Wins
1 Cleveland 50 Denver 49
2 Orlando 49 Dallas 48
3 Atlanta 48 San Antonio 48
4 Boston 47 Oklahoma City 48
5 New York 47 New Orleans 47
6 New Jersey 47 LA Lakers 46
7 Detroit 35 Sacramento 46
8 Milwaukee 35 Portland 45
9 Toronto 35 Golden State 44
10 Miami 35 Minnesota 36
11 Chicago 34 Houston 36
12 Indiana 34 LA Clippers 35
13 Philadelphia 34 Memphis 34
14 Charlotte 34 Phoenix 34
15 Washington 33 Utah 33

Five games in:
Standing Eastern Conference Wins Western Conference Wins
1 Miami 58 LA Lakers 64
2 Atlanta 57 New Orleans 62
3 Orlando 53 San Antonio 50
4 Boston 51 Golden State 49
5 New York 46 Portland 48
6 Cleveland 39 Sacramento 46
7 Chicago 38 Denver 46
8 New Jersey 36 Dallas 45
9 Indiana 33 Oklahoma City 41
10 Toronto 32 Memphis 38
11 Milwaukee 29 Utah 38
12 Philadelphia 28 Phoenix 37
13 Charlotte 27 LA Clippers 30
14 Washington 27 Minnesota 26
15 Detroit 22 Houston 23


Ten games in:
Standing Eastern Conference Wins Western Conference Wins
1 Boston 57 New Orleans 65
2 Miami 51 LA Lakers 57
3 Orlando 50 Dallas 57
4 Chicago 47 San Antonio 56
5 Atlanta 44 Utah 52
6 Milwaukee 44 Phoenix 49
7 Cleveland 38 Oklahoma City 45
8 Indiana 37 Portland 44
9 New Jersey 35 Denver 43
10 Detroit 34 Golden State 41
11 Charlotte 30 Memphis 38
12 New York 28 Houston 31
13 Washington 28 Minnesota 29
14 Toronto 28 Sacramento 28
15 Philadelphia 26 LA Clippers 21