SB Nation User Blog: PoliSam

For your consideration. The proportion of minutes played by the most common 5-man unit on each team...

PoliSam — Thu, 05 Nov 2009 19:22:21 -0000

For your consideration. The proportion of minutes played by the most common 5-man unit on each team in the NBA so far (normally the starters, but not always). I'm not sure what it means, but found it interesting.

Note that a few of the teams below the Blazers have had to change starting line-ups due to injury in the middle of this season, like Orlando with the injury to Carter or Charlotte with Bell coming back from injury.

Glass half-full: the guys have not played enough together to gel. When they do, the team will be dominating.

Glass half-empty: Nate is making rotations too quickly; Oden cannot avoid foul trouble, so the Blazers are doomed.

2009-2010 Regular Season Prediction Contest

PoliSam — Tue, 27 Oct 2009 14:00:32 -0000

I don't know about the rest of you, but for me Dave's reminder that the glorious Blazersedge Jersey Contest does not start until November was a major gameday buzz kill. I had my Excel Spreedsheets, Stata 10.0, and favorite stat websites all set-up and ready to roll. But now I see that they'll have to sit idle for a couple more days... Arrrgh! What fun is a Blazers game if it does not provide me with the opportunity to prove that I am not as good at predicting the future as I think I am? What fun is the day after the game if I don't get to see how poorly other people--especially people that disagree with me--did in the Jersey Contest???

Fortunately, I decided that I should not spend the day sulking, wishing Blazersedge was different than it is. I decided that instead of being a victim, I should take action into my own hands! I should create my own **** contest!! No, not my contest. Our contest. And it wont be for one game. It will be for the entire season! Take that, Dave. Ha-ha! Yes, a prediction contest for the results of the season. Perfect. It will take a lot of patience--it's for the Bedgers that know that they will be here April 15th, 2010, even if Brandon Roy, LaMarcus Aldridge, and Greg Oden all go down with season ending injuries today... But, it should be a fun way to test a different aspect of our prognostication skills... or..er... luck.

Okay, great.... So, will there be a prize for this contest? Well, that's putting the cart before the horse. First, I need to figure out if the results will be scored. Unfortunately, there are no guarantees there. I'm pretty clever with inputting data, but I don't know how to create one of those cool submission forms (i.e. http://blazersedge.reaxion.org/gameform.php) and I may be incredibly busy in April. Perhaps a collective effort will get the job done? We'll just have to see. EDIT: That being said, I will probably be able to do it, so expect to see a post summarizing the scoring some time in April. Assuming the results are scored, then I'll gladly send a (cheap) Blazer-themed prize to honor the winner. If other s feel similarly compelled to reward greatness, perhaps resources can be pooled and the prize will be somewhat cool. EDIT: At the very least, the winner will be able to add, "I dominated Jscot in the Regular Season Prediction Contest!" to the signature of his or her posts.

On to the questions.

The Biggies

1. How many games will the Blazers win this season? (20 points possible, -2 points off for each win off)

2. Will the Blazers win the Northwest Division? (10 points)

Blazer Statistics. For all questions concerning season averages, the numerator will be the number of games that the player or players in question actually entered (not 82 games).

3. Which will be greater, (a) Kevin Durant's per game scoring average +3, or (b) Brandon Roy's per game scoring average? (2 points)

4. How many rebounds will Greg Oden average per game? (4 points possible, -1 point for each rebound off)

5. How many assists with Andre Miller average per game? (3 points possible, -1 point for each assist off)

6. Which will be greater, (a) LaMarcus Aldridge's rebounds per game+points per game, or (b) the sum of the per game scoring averages of Blake, Pryzbilla, Outlaw, and Batum? (2 points)

7. How many three pointers made per game will Rudy Fernandez average? (2 points possible, -1 for each .25 of a three pointer off)

8. How many games will Jerryd Bayless play (for the Blazers)? (2 points possible, -1 for every 5 games off)

9. What FG% will Jerrdy Bayless shoot (for the Blazers) ? (rounded to the nearest whole percentage, e.g. 36%, his projected FG% on espn.com. 2 points possible, -1 for every 3 percentage points off)

10. What FT% will Greg Oden shoot? (rounded to the nearest whole percentage, e.g. 64%, his projected FG% on espn.com. 2 points possible, -1 for every 2 percentage points off).

Over-Unders for Regular Season Wins. For the following questions, answer by saying whether the team's regular season win total will be over or under the number next to it. (2 points each)

Western Conference

11. LA Lakers 61.5

12. Denver Nuggets 52.5

13. Utah Jazz 49.5

14. Oklahoma City "Thunder" 34.5

15. Minnesota Timberwolves 25.5

16. Houston Rockets 35.5

17. San Antonio Spurs 54.5

18. Dallas Mavericks 49.5

19. Phoenix Suns 40.5

20. LA Clippers 34.5

Eastern Conference

21. Cleveland Cavs 61.5

22. Orlando Magic 58.5

23. Boston Celtics 58.5

24. Chicago Bulls 40.5

25. Toronto Raptors 40.5

26. Detroit Pistons 40.5

27. Indiana Pacers 34.5

28. New Jersey Nets 27.5

Miscellaneous (2 points each)

29. Will LeBron James win the MVP?

30. Will Dwight Howard win the defensive player of the year Award?

See my response below for the preferred answer format. The cleaner your entry, the more likely that it will actually be scored someday!

Okay. That should help you waste a few minutes while waiting for tonights game. Good luck!

Poll

Is Dave cruel for not giving us a practice jersey contest for the first game?

Yes

19 votes

19 votes | Poll has closed

Preseason Stats

PoliSam — Tue, 20 Oct 2009 21:36:35 -0000

Preseason Stats

Because they are so, so meaningful. Also, because Oden is averaging 30pts, 20 rebounds, and 3 blocks per 48 minutes (which would be 20pts, 13 rebounds, and 2 blocks per 32 minutes, fwiw).

Notable over-unders for season win totals

PoliSam — Thu, 08 Oct 2009 22:23:12 -0000

Notable over-unders for season win totals

Portland 52.5
LAL 61.5
Cleveland 60.5
San Antonio 54.5
Denver 52.5

ESPN Fantasy Basketball Predictions for the Blazers

PoliSam — Sat, 26 Sep 2009 12:29:10 -0000

ESPN Fantasy Basketball Predictions for the Blazers

Very detailed. Nothing too controversial, but still interesting. A few thoughts:

I think the player with the best chance to exceed their projections is Oden.

I found their minute projections especially interesting, with Miller playing 32 minutes per game and Blake playing 20 (with the games played projection, it works out to just barely more than the 48 minutes at PG). They split the SF minutes fairly evenly and kept Rudy's minutes unchanged.

I'm ready for training camp to start!

8-18 Junk Drawer, Wicker Edition (update with graph)

PoliSam — Tue, 18 Aug 2009 08:40:24 -0000

When I think of the "first" basketball hoop, I have in mind a wicker basket that looks something like this:

Apparently, however, Dr. Naismith's first hoop wasn't really wicker, at least that's not how I would describe the basket in this photo:

via www.authenticbasketball.com

I was thinking of wicker baskets because I was thinking about technological progress in sports after Usain Bolt ran a 9.59 in 100 meters. I am skeptical that he's truly half of a second faster than the world champions of 10 years ago--by which I mean, I am skeptical that if Carl Lewis was running in this era would he really be half of a second behind Bolt. It also seems like an unlikely coincidence that Tyson Gay set a U.S. record in the same contest.

The question that I have been debating with others (though mostly myself) is why times in the 100 meter dash are still dropping. Is it improved training? Finding the right athlete for the race? Shoes? Track surface? Performance enhancing drugs? World records have been falling in swimming at an alarming rate, but there the swim suits are obviously involved. Records fall much less frequently in the Long Jump and other distances. What's going on in the 100? The graph below shows just how dramatic is the recent decline:

via chartingtheeconomy.com

The record stood at 10 seconds in 1956. 9.9 something until 1988 (remember Ben Johnson) and then falls two tenths of a second in 3 years??? Today's best long jumpers almost never beat what Bob Beamon jumped in 1968!

This also raises a question relevant to basketball: If basketball was measured "objectively" would LeBron James be 5% better than Michael Jordan? Are basketball players improving as much as track athletes? If not, why not? I recently watched a little of the 1980 NBA championship and I can say without hesitation that the 1980 Lakers would not have a winning record in today's NBA. The Lakers did not have the type of athletes or all around skill that today's NBA players have. It's not even close. I'm curious to hear others thoughts on the issue.

That's my contribution of junk!

Poll

Usain Bolt is to Carl Lewis as

LeBron James is to Michael Jordan

8 votes

LeBron James is to Magic Johnson

12 votes

LeBron James is to Oscar Robinson

11 votes

LeBron is terrible. Long live Kobe!

4 votes

Other

14 votes

49 votes | Poll has closed

Predicting Wins in 2009-2010, Consider "Regression to the Mean"

PoliSam — Wed, 05 Aug 2009 15:21:35 -0000

With the release of the 2009-2010 NBA schedule yesterday, we saw the first wave of predictions for the upcoming season. In making predictions for the Blazers or any other team the first thing most people consider, whether explicitly or implicitly, is a team's record the previous season. The previous season serves as a baseline in our mind and then we try to figure out if the team will improve or get worse. By and large, this is a sensible way of thinking.

However, an additional consideration that should go into our thought process--but that we often forget--is a phenomenon called regression to the mean. Regression to the mean is a technical term in probability and statistics that refers to the fact that, left to themselves, things tend to return to normal, whatever that is. The term was coined by Francis Galton, inventor of the regression, when he noticed that the offspring of very tall parents tended to be shorter than their parents--at least that's the story they always tell in statistics classes. Regression to the mean in NBA wins would imply that teams that tend to win a lot of games in one season are more likely to win fewer games the following season, or conversely that teams that win few games in one season are more likely to win more games the following season. In other words, a 60 win team in 2009 is more likely to win 55-59 games than 60-64 in 2010, while a 25 win team in 2000 is more likely to win 26-30 games than 25-21 games in 2001. Does this happen in the NBA? Indeed it does. In fact, regression to the mean is quite pronounced and holds controlling for the average age of teams. Details below.

Regression to the Mean in wins from Season to Season, the NBA from 1956 to 2009

It is actually fairly easy to assess the importance of regression to the mean in wins from one season to the next in the NBA. Team season records are readily available at basketball-reference.com or databasebasketball.com and the empirical question is straightforward: do teams tend to win fewer games the following season if they are above the mean number of wins (41)? There are a variety of ways to answer this question analytically, all of which point toward regression to the mean being quite robust. To demonstrate that this occurs, I have simply graphed the average change in the of number of wins as a function of wins in the previous season for all teams from 1956 to 2009:

The graph shows that teams that have won 40 or 41 games the previous season, win about 40 to 41 games on average the next season, because the average change in the number of games is about 0. As teams move in either direction of average, however, regression to the mean occurs. Teams that win 46 games a season, tend to win about 2 fewer games the following season (44). In contrast, teams that win 37 games in one season win, on average, about 3 more games the next season (40). In addition, the farther a team moves away from the mean, the stronger the pull of the mean. 60 win teams win, on average, about 6 fewer games the following season (54), while 25 win teams tend to win about 6 more games the following season (31).

In common language, this graph shows that bad teams tend to get better and elite teams tend to get worse. A fairly sensible implication of this pattern is that, as many have suggested, going from 54 to 60 wins is "harder" than going from 40 wins to 46 wins. Why is true? There are a variety of possible reasons, but the most important one is probably luck. Teams that do well tend to avoid injuries, have favorable schedules, and win close games. Teams with bad luck (injuries, bad chemistry, or bad bounces) tend to see their fortunes brighten the following season simply because average luck is more likely than bad luck. I was fairly confident that I would see evidence of regression to the mean in the data, but the strength, regularity, and linearity of the pattern surprised me. I figured that the graph would be fairly flat around the middle, with teams with 35 to 47 wins not regressing to the mean much, but truly elite and terrible teams regressing to the mean quite strongly.

Regression to the Mean in wins from Season to Season, the NBA from 1980 to 2009

To check on the robustness of this pattern, consider the graph below, which restricts the analysis to season from 1980 to 2009. Though the graphs look almost indentical, they are run on different data, which is one indication of how regular this pattern is:

Is it all about Age?

One might wonder if this trend is simply a reflection of something that we've talked about before, age. That is, is the tendency for bad teams to get better and elite teams to get worse, simply a reflection of the fact that "bad" teams are really just younger teams and elite teams are full of veterans? The short answer is no. While it is true that older teams tend to get worse and younger teams tend to get better (with the break even point being an average age of 27 years), regression to the mean is still strong controlling for age. In other words, teams with an average age greater than 27 tend to have a worse record the following season, but the higher the number of wins the previous season, the worse their record.

To illustrate this, the graph below shows the average change in number of wins as a function of previous wins, controlling for a team's average age in the previous season. (For those that care, the y-axis is actually the residuals from a regression of change in wins on the age of a team in the previous season). That the slope of the line in this graph is less steep indicates that age was driving some--but not all--of the pattern in the previous graphs.

So what does this mean for the Blazers in 2009-2010?

Since the Blazers were both very young and very good in 2009, what should we expect in 2010? The youthfulness of the Blazers suggest that they should improve, but improving from 54 wins is very difficult. In particular, teams that have won 54 games have won an average of 51 games the following season. On the other hand, teams of an average age of 24 to 25, win about 5 additional games the following season. Quick and dirty regressions of wins on a set of dummy variables for wins the previous season and age the previous season yields a prediction of 54-56 wins for the Blazers in 2010, depending on some minor technical assumptions. While I do not believe that theses are the only factors one should consider in projecting the Blazers season in 2010, I also would not ignore them. If you think that the Blazers are going to win more than 54-56 games in 2010, it should be because you believe the additions of Andre Miller and improvement of Oden and other players will make-up for the normal regression to the mean that occurs in the NBA.

Lastly, for those of you that are not interested in averages, graphs, regressions, and whanot, below is a list of the team records for all teams following a season of 54 wins (so, LAL won 54 games in 62, but 43 games in 63):

Team	Year	Wins	Age prior year
PH1	1960	48	26.43747
LAL	1963	43	26.49471
BOS	1968	48	30.05789
NYK	1969	60	26.63787
CHI	1974	47	29.21364
BOS	1976	44	29.32505
WA1	1979	39	28.55113
LAL	1981	57	27.44369
LAL	1984	62	28.10951
PHI	1986	45	28.51308
DEN	1988	44	28.99218
DET	1988	63	27.97651
PHO	1990	55	27.21177
UTA	1991	55	29.1215
CLE	1993	47	29.28346
CHA	1997	51	29.47461
DET	1997	37	28.57562
IND	1999	56	31.22052
ORL	1999	41	29.17436
MIA	1999	52	30.66639
DET	2004	54	27.88333
DET	2005	64	28.37027
PHO	2006	61	28.01781

As you can see, some 54 win teams improved, more got worse. In addition, last year's Blazers, with an average age of 24.5, is far younger than all previous 54 win teams. Thus, there is no perfect historical analogy for the current team.

Nonetheless, seeing the strength of regression to the mean in the NBA probably has made me a bit more skeptical about the Blazers chances of winning 60 games in 2010 (my original prediction), and it has had an even bigger impact on the way I will think about the rest of the league in 2010. Anyway, this is far from the final word on making projections for the coming season. It's just an interesting pattern that is easy to document that I thought the Blazersedge community might find interesting. Does this change your outlook on the Blazers in 2009-10? For other teams? Why or why, not?

Any alternative explanations, comments, questions, or suggestions for additional analysis?

Batum Leads France with 15pts, 5 Assists against the Czech Republic

PoliSam — Mon, 27 Jul 2009 15:05:29 -0000

Batum Leads France with 15pts, 5 Assists against the Czech Republic

Pretty nice stat line for Nic!

Does anyone have additional info on this game? Like, when was it played?? I started searching for the box score when I saw a story about Parker hurting his ankle against Austria... I was surprised to see that France has played two games and yet no reports from our European Blazer fans.

Oden Story from Las Vegas Review-Journal

PoliSam — Sun, 26 Jul 2009 16:29:49 -0000

Oden Story from Las Vegas Review-Journal

Interesting to get a third-party perspective.

For a first-party perspective, Casey has a nice summary:

More Oden

Sergio Wants Out "I don't know what my future (is) going to be," Rodriguez said. "I think...

PoliSam — Sun, 03 May 2009 17:40:18 -0000

Sergio Wants Out

"I don't know what my future (is) going to be," Rodriguez said. "I think something is going to happen, either a trade, or something. But I think for me, I feel like I need a change. I need to play a different way. I really enjoy playing three years here. But I think I need something (different). I feel after three years, I need a change."

http://blog.oregonlive.com/behindblazersbeat/2009/05/pritchard_the_puzzle_master.html