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06 Oct 2011

FEI: Visualization

by Brian Fremeau

On Saturday night, the Alabama Crimson Tide made another big statement. The Florida Gators are dangerous and talented, especially in the Swamp, and they threw their best punches in the first quarter to take an early lead against the Tide. But the dominant Alabama defense settled in and took over for the final 50 minutes of the game.

After giving up 10 points on the first two Florida drives, the Tide made up that deficit with an Courtney Upshaw interception return early in the second quarter. After the early drives, Alabama allowed only one other Florida possession to enter the red zone the rest of the night. And immediately after surrendering that red zone trip, Alabama sacked Gators quarterback John Brantley on consecutive plays to force a failed 52-yard field goal attempt and knock Brantley out of the game. Florida would not cross the 50-yard line and would earn only two first downs in the second half.

The victory moved Alabama alongside LSU as a neck-and-neck 1-2 in the FEI ratings. The showdown that looms on November 5th between these SEC West behemoths could be one for the ages. Both the Tigers and Tide have excellent defenses that have won games all on their own. Big defensive sacks and tackles for loss, turnovers creating field position advantages, returning turnovers for scores -– there are plenty of flashy ways that a defense can take over a football game. But what does it look like when a defense is simply, consistently winning possession-by-possession?

According to my unit splits analysis, Alabama’s defense had contributed only about one point to the cumulative seven point scoring margin for the Tide at the conclusion of Upshaw’s interception return. By the end of the game, Alabama’s defense had contributed an additional 10 points in scoring margin value. In other words, over the next 15 game possessions, Alabama’s offense and defense earned a roughly equal share of the victory.

The Tide offense leaned on a punishing ground game led by Trent Richardson’s career-high 181 yards, but it wasn’t a consistently thorough offensive beating. Alabama went three-and-out twice in the second half and the ground game was stuffed on two other drives after moving into Florida territory. Three touchdown drives, one set up by a short field following a Florida fumble, did plenty of damage and reinforced the hopelessness of a Florida comeback.

The following chart is a visual representation of the game specifically designed to illustrate the cumulative contribution of the offense, defense, and special teams value earned on each drive.

The visualization of college football games is an ongoing project I'm looking to develop throughout the year and into the future. Drive charts have been around for a long time (see this account of the 1927 Rose Bowl), but we can create even richer visual accounts of the game by illustrating some of our more advanced metrics. I'm looking forward to receiving feedback on this particular visualization to enhance these graphics going forward.

FEI Week 5 Top 25

The Fremeau Efficiency Index (FEI) rewards playing well against good teams, win or lose, and punishes losing to poor teams more harshly than it rewards defeating poor teams. FEI is drive-based, not play-by-play based, and it is specifically engineered to measure the college game.

FEI is the opponent-adjusted value of Game Efficiency (GE), a measurement of the success rate of a team scoring and preventing opponent scoring throughout the non-garbage-time possessions of a game. FEI represents a team's efficiency value over average. Strength of Schedule (SOS) is calculated as the likelihood that an "elite team" (two standard deviations above average) would win every game on the given team's schedule. SOS listed here includes future games scheduled.

Mean Wins (FBS MW) represent the average total games a team with the given FEI rating should expect to win against its complete schedule of FBS opponents. Remaining Mean Wins (FBS RMW) represent the average expected team wins for games scheduled but not yet played.

Only games between FBS teams are considered in the FEI calculations. Since limited data is available in the early part of the season, preseason projections are factored into the current ratings. The weight given to projected data will be reduced each week until Week 7, when it will be eliminated entirely. Offensive and defensive FEI ratings will also debut in Week 7.

These FEI ratings are a function of results of games played through October 1. The ratings for all FBS teams can be found here.

Rank Team FBS
W-L
FEI Last
Wk
GE GE
Rk
SOS SOS
Rk
FBS
MW
FBS
RMW
1 LSU 4-0 .304 1 .234 12 .097 8 9.6 6.1
2 Alabama 5-0 .303 3 .342 5 .134 19 9.2 5.0
3 Oklahoma 4-0 .298 2 .359 3 .186 40 10.7 7.1
4 Wisconsin 4-0 .247 4 .600 1 .467 95 10.1 6.2
5 Clemson 4-0 .244 5 .162 19 .206 43 9.2 5.9
6 Michigan 5-0 .241 10 .347 4 .341 74 10.3 5.7
7 Stanford 4-0 .227 9 .405 2 .513 103 11.0 7.1
8 Georgia Tech 4-0 .225 15 .340 6 .441 92 9.3 5.5
9 West Virginia 3-1 .215 13 .138 20 .161 28 8.3 5.3
10 Oklahoma State 4-0 .211 6 .227 13 .156 25 9.8 6.3
11 Boise State 4-0 .191 7 .238 11 .640 112 11.3 7.7
12 Arkansas 3-1 .187 21 .094 33 .075 5 7.2 4.7
Rank Team FBS
W-L
FEI Last
Wk
GE GE
Rk
SOS SOS
Rk
FBS
MW
FBS
RMW
13 Texas A&M 2-2 .184 14 .198 15 .099 9 8.8 5.8
14 Florida 4-1 .177 8 .239 10 .075 4 8.3 4.0
15 Oregon 2-1 .172 11 .168 17 .166 29 9.0 6.8
16 Notre Dame 3-2 .164 17 .114 24 .159 27 8.9 5.7
17 Pittsburgh 2-2 .160 25 .098 32 .195 41 6.9 4.7
18 Tennessee 2-1 .140 31 .226 14 .065 2 5.9 4.2
19 Iowa 2-1 .131 26 .103 29 .427 91 8.3 6.0
20 Arizona State 3-1 .124 20 .108 27 .302 63 8.5 5.5
21 Florida State 1-2 .118 19 .054 46 .147 22 8.3 6.8
22 North Carolina 3-1 .115 44 .088 35 .173 31 6.0 4.1
23 Texas 4-0 .110 38 .269 8 .121 17 6.4 3.4
24 South Carolina 4-1 .109 12 .088 36 .179 35 7.9 3.8
25 Michigan State 3-1 .109 36 .162 18 .175 32 6.3 3.8

Posted by: Brian Fremeau on 06 Oct 2011

4 comments, Last at 06 Oct 2011, 5:48pm by DisplacedPackerFan

Comments

1
by Ununanonymous (not verified) :: Thu, 10/06/2011 - 1:32pm

Wisconsin's GE?

Still sick.

2
by DisplacedPackerFan :: Thu, 10/06/2011 - 3:36pm

Yeah, it fell from .700 to .600 I think. It's only .195 better than #2, I think that shrank from .285 last week. But it's still crazy.

What is the best GE for a season, I'm trying to get a better context.

3
by Joseph :: Thu, 10/06/2011 - 5:03pm

Re: the graphs, the first one is great. The 2nd one, not so much.

4
by DisplacedPackerFan :: Thu, 10/06/2011 - 5:48pm

I agree. Though I think the 2nd one is valuable it just needs tweaking to make it easier to "read."

The second one would work better with better coloring, and honestly arrows. I like it better than a standard drive chart, and while the direction can be followed arrows for flow direction would speed up visual processing or "glance" processing. The first down markers are too close to the red, the drive start markers are the same as the UF bars. They get lost. This can be fixed with better color or perhaps doing a more distinct shape outside the bar with a uniform break line across the bar. A sharper edge on the shape when you have similar colors will help the data point stand out. Both would be better, but using team colors is not a bad idea for the bars. I'm not sure if having different FD mark colors per team would help or hurt.

I think you need additional field lines too. 30's and 10's maybe though maybe just 20's since that is where the "field changes" enough that it affects the play calling (or so we are told). But adding something in as an additional horizontal eyeline anchor would help. The more I look I think just the 20's (like the 50 is marked) would work. Bounding the goal line might help too.

Trying to convey how the yardage was gained in a general sense like this does carry good info, I just don't think it's presented as cleanly as it could be. Hope the comments help.

I've wondered about drive charts as a "standard bar graph". I see some of the point as to rapidly processing the flow of a game. All drives having the same start point on one access and then just a TO/FG/P/TD/DW marker at the end of the bar. You could still do the variable width to indicate offense vs special teams/defense. This loses all the field position information though, unless that becomes another number on the bar.