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Statistically Speaking: ACC Rewind: SDPI

Thursday, February 08, 2007

ACC Rewind: SDPI

One way to look at team strength, taken from Eddie Epstein’s fantastic book Dominance, is to look at teams points scored and allowed relative to the league average and standard deviation. The more standard deviations they are from the mean, the better (or worse they are). For those unfamiliar with what standard deviation is here’s the wikipedia link. In the coming weeks, I will be looking at each Division IA conference and ranking each team in regards to their Standard Deviation Power Index in conference play. Keep in mind, the SDPI does not adjust for schedule strength for conferences such as the ACC where each team does not play each other and it ignores special teams which can play a significant role in both points scored and points allowed.

If you want the meat of the article, skip this next paragraph as it just gives an example of how the SDPI is calculated. The mean points scored and allowed for all ACC teams in conference play (championship game not included) was 162 points. The standard deviation for points scored was 35.97. The standard deviation for points allowed was 51.18. Coastal Division champ Georgia Tech scored 213 and allowed 155 points. Georgia Tech’s offensive SDPI was 1.42 = ([213-162]/35.97). Their defensive SDPI was .14 = ([162-155]/51.18). Their total SDPI was 1.55 (not 1.56 because the other two were rounded). In the 2006 ACC, that was good for third best.

First here's the link to the 2006 ACC Standings to refresh your memory.

Now here are the 2006 SDPI Standings.

Virginia Tech 2.02
Clemson 1.81
Georgia Tech 1.55
Boston College 1.32
Wake Forest 0.69
Florida State 0.42
Virginia -0.15
Miami -0.29
Maryland -0.45
NC State -0.93
North Carolina -2.63
Duke -3.36

If you thought Wake Forest was doing it with smoke and mirrors, well you were probably right. SDPI has Wake Forest as an above average, but middling team (5th place in the league). The league’s best team, according to SDPI, did not get to participate in the title game thanks to their mid-season struggles. Although 3 of the 4 Tobacco Road schools finished with at least 6 losses, its clear North Carolina and Duke were in a league of their own in terms of ineptitude.

Best Offense: Georgia Tech 1.42
Despite the best efforts of Reggie Ball the Yellow Jackets did post the league’s best offensive SDPI.

Worst Offense: North Carolina -1.47
Yes they were worse than Duke.

Best Defense: Virginia Tech 1.35
In their last 4 conference games, the Hokies gave up 23 points.

Worst Defense: Duke -2.31
Held only one team to under 20 points (Wake Forest) and still lost thanks to a blocked field goal. Interestingly, the best and worst from each category all came from the Coastal Division.

Best Team that Didn’t Go to a Bowl: Virginia -0.15
The Cavs were 4-4 in the ACC (about what you would expect given the almost average ranking), but failed to go bowling thanks to a 1-3 mark in non-conference play.

Worst Team that Went to a Bowl: Maryland -0.45
All 5 of their conference wins came by 6 points or less, including two by a single point, one by two, and one by three.

Toughest Schedule (ranked by sum of opponent’s SDPI): Maryland 4.42
Maybe that’s why they played so many close games. No Hokies, but also no Heels or Devils on the schedule.

Easiest Schedule (ranked by sum of opponent’s SDPI): Georgia Tech -3.98
Jackets had the easiest schedule and won their division. Coincidence? Played the Atlantic’s best (Clemson), but also the two worst (Maryland and NC State).

Entire Schedule Strength (hardest to easiest)
Maryland 4.42
Duke 2.93
NC State 2.56
Clemson 1.99
North Carolina 1.34
Boston College -0.09
Virginia Tech -1.06
Miami -1.28
Florida State -1.36
Wake Forest -1.80
Virginia -3.67
Georgia Tech -3.98

Team(s) Likely to Decline: Wake Forest and Maryland
The Deacs are not going to win the ACC again next year obviously, but should be competitive and go to a mid-level bowl game. Maryland’s unbelievable luck in close games will not continue and don’t be shocked to see The Fridge’s boys in the Atlantic basement next season.

Team(s) Likely to Improve: Virginia and NC State
The Cavs were a very young team in 2006, but were still actually about average. Expect 2007 to be Groh’s best in Charlottesville. NC State finished 2-6, but they were much closer to Maryland in terms of SDPI than either of their basement brethren on Tobacco Road. Tom O’Brien was a great hire and NC State will contend for a bowl game in 2007.

4 Comments:

Blogger Jeff said...

Great analysis and an interesting take. The one thing I question is the point about NC State. While Tom O'Brien might be a good coach I do not think he was a great hire. NC State could attract a big name with big recruiting pull. I just do not think they got that. We will see, but living in the south I know the fans will get nervous when they lose a game to a team they should easily beat.

Thanks.

6:55 AM  
Blogger T.L. Koontz said...

I agree, your analysis was pretty spot-on. . . And, I DO agree with your NC State prediction.

Come on, Jeff, to say TOB was not a great hire is to be in total denial! He is the answer to the Wolpack's discipline issues--which were the main reason they lost the vast majority of their games... Likewise, NC State is exactly the kind of school TOB needs to become a coaching legend--great facilities and vast resources, as well as a rabid fanbase. Those were two major reasons BC hit the glass ceiling!!

10:43 AM  
Blogger matt said...

Thanks for the comments guys. I may be a bit biased, but I believe Tom O'Brien is one of the best coaches in the nation in terms of doing the most with what he's been given. I did a little analysis of his career back in December on this blog. In regards to NC State, there's no way they can be as unlucky as they were last season--they had the 3rd toughest conference schedule and they were 2-7 in close games. Simple regression (or progrssion) to the mean in that department will have the Pack bowling in TOB's first season.

3:21 PM  
Anonymous Anonymous said...

Can't say that I agree that Wake Forest will obviously not win the ACC next year. Have you seen how easy the schedule is? They avoid Miami, Georgia Tech, and Virginia Tech.

6:23 PM  

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