Thursday, October 01, 2009

Premature Power Poll

Or why Iowa Deserves Some Respect

Every season we do our Power Rankings based on the following formula (USC from 2008 after game 6 is used as an example here)–

((SD Ratio *1.1) + (SO Ratio *0.9) + W/L Record)) * SOS = Power Value

Explained further –

SD Ratio is a ratio of each team’s scoring defense to the best scoring defense. For example USC has the top scoring defense in the nation at 7.8 ppg. New to this year we apply a multiplier of 1.1 based on my work that found a high correlation of scoring defenses to success. So USC, with the best scoring defense gets a 1.1 in this category (1*1.1).

SO Ratio is a ratio of each team’s scoring offense to the best scoring offense. Using the USC example, their offense is 8th overall at 41.5 ppg. The best offense is Tulsa’s at 56.7 ppg. Thus USC’s ratio is .7336 of the best. Then we apply a 0.9 multiplier reflecting the relatively lesser importance of offense to defense, and get 0.66024.

W/L record is a simple calculation of % record, in USC’s case 0.83333 (5-1).

We add the three components together, in our example totaling 2.5936. Then the number is multiplied by the strength of schedule per the NCAA, which in USC’s case is a ratio of 0.692308 (40th nationally having played teams that are 18-15). The end result is 1.795553.

It has, in my opinion, done an excellent job in the past of determining the relative strength of the teams. Coincidently, the number one team in each of our past three Final Power Rankings has been the BCS Champion for that year. This has occurred despite the unbiased nature of our ranking system.

I usually wait until after 8th week to start the Power Rankings as I believe the data inputs are not solid enough until then, especially the SOS rankings.

As I was preparing the rankings for later use, I was surprised by some of the current rankings, and decided they were worth sharing. They are –

1 Oklahoma
2 Florida
3 Iowa
4 Virginia Tech
5 Houston
6 North Carolina St.
7 Kansas
8 Michigan
9 Oregon
10 Arizona
11 West Virginia
12 Clemson
13 Mississippi St.
14 Cincinnati
15 Georgia Tech
16 Iowa St.
17 Georgia
18 Fresno St.
19 California
20 Washington
21 Ohio St.
22 Florida St.
23 LSU
24 Arizona St.
25 North Carolina

Oklahoma, with the top scoring defense and a decent SOS, gets the top slot. Undefeated Florida, with high rankings in scoring defense and offense, comes in second.

Then we have undefeated Iowa. Why?

Well the Hawkeyes offense is middle of the road, though their defense is pretty good, giving up only 11.5 ppg. But, so far, their opposition is undefeated (except for their collective losses to Iowa).

That’s right, Northern Iowa, Iowa State, Arizona and Penn State have lost only to Iowa, and are otherwise unbeaten.

And the same is true with Virginia Tech! The teams the Hokies have played are a collective 10-0 in games not against Tech. Which is pretty remarkable, even after the 4th week.

There is, of course, much not to like about doing the rankings this early, and the SOS needs more time to even out, as do the key underlying stats. But look how this compares to the conventional polls.

LSU is 23rd here, while 4th in the polls. Reason? Their current SOS stinks.

Where is Alabama and USC? In our current, admittedly flawed, rankings they are 34th and 43rd, respectively. Once again it is about schedule strength. Alabama’s current past opponents are 4-5, giving the Tide the 75th ranked SOS, while USC’s are 5-6 for the 74th ranked SOS.

Once again this is very, very early, and we usually don’t Power Rank this soon. But there is food for thought here. Perhaps teams like Iowa and even Michigan are better than conventional wisdom holds, while teams like LSU, Alabama and USC really haven’t been tested.

1 comment:

Amos said...

I guess I may have to get over my complete dismissal of Iowa after week one and start keeping an eye on them again.