In the comments in my previous post, reader & commenter extraordinaire some dude
(who’s a Lakers fan but we forgive him) wrote:
Kings, Clips, W’s all got better in the west IMO. Only team above NOH that definitely got worse is Phx. I maintain Houston is better now that Yao is back, though your model disagrees. Portland should be better too. NOH didn’t improve enough to matter.
I was looking over your over/under article and it just feels like the West has too many wins. too many teams over 35 wins. In fact, I see you only predicted 2 total teams in the West below 35 wins. Sorry Arturo, but that’s not realistic. Has that ever happened for a conference?
I’m only trying to help you. Something seems off. There’s no way 13 of 15 Western teams are going to be close to .500 teams or above, which is what you got. Not when you play 52 games against each other and injuries happen and quite a few Eastern teams got better.
I'm making this SD's theme image
I looked at this comment and thought about it real hard. A funny thing happened this NBA offseason while everyone was distracted by the goings on in South Beach. While a few teams in the East got better, the entire Western Conference improved. Can I show this with some tables? Of course, I can.
League Balance since 2005
Let’s look at the balance between the conferences since 2005 (when the Bobcats joined the league).
Since 2005 for the most part the western conference has been dominant. If we look in detail at 2010:
We see that while the typical western team produced about 2 more wins and won about 3 more, the difference in the average opponent was only about half a win. How did I work this out? Since a team plays 52 games in conference and 30 out of conference the opponent adjustments work out to:
Avg. Opponent Raw Wins (East)= (52*Raw Wins by Team(East) +30*Raw Wins by Team(West))/82
Avg. Opponent Raw Wins (West)= (52*Raw Wins by Team(West) +30*Raw Wins by Team(East))/82
What this means is that out of 82 games, every team plays 58 games that are the same and 24 that are conference and team driven. So if there’s a difference in the conferences the impact to strength of schedule will nave to be reduced by multiplying it by 24/82 . This is why I discounted strength of schedule in a previous post and while this is generally a good rule of thumb this upcoming season is the exception to the rule.
Lack of Parity in 2010-2011
So we know the west was stronger last season and we also know that there was a massive sea change in rosters this offseason. How badly did the change hurt the East?
Badly. On average every team in the west got 1.84 wins better and the every team in the east got 1.84 wins worse. When I work out the average opponent raw wins, I get:
Avg. Opponent Raw Wins (East)=125.1
Avg. Opponent Raw Wins (West)= 126.8
This means that the same team could win an additional 2 games by switching from the West to the East. Color me surprised, I’m actually going to have to work the schedule into my final projections.
No comment required
Note: Final Preseason picks will be up tomorrow, followed by a team review (a really obvious one) and final predictions on Monday.
Arturo's Silly Little Stats v2.0 
some dude
10/22/2010
Ooh, this was an interesting post. Makes sense for those changes in the average team.
How does this work at the ends, though? What kind of bump does the bottom feeders of the West get compared to the drop in the East (if you can work that out).
I think 2007 was the season with the biggest gap. I’m fairly convinced 6-7 teams out West could have been a top 2 seed out East that season.
arturogalletti
10/22/2010
add 2 wins to every team in the east, subtract two in the west.
some dude
10/23/2010
but should the distribution of games matter?
For instance, the Lakers might only lose 1 game because they’re the best team out West while the T-wolves lose 4 games. The average is 2, but the ends might have different results.
arturogalletti
10/23/2010
Not really. It’s a marginal value calculation. The wins generated by the lakers and T-wolves won’t vary just the opposition.