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28 Aug 2013

FEI Preseason Primer Part II

by Brian Fremeau

In Part I of the FEI preseason primer posted last week, I discussed in detail the factors that went into this year’s FEI projections. Program FEI remains the foundation of the projection model, but new factors include last year’s garbage-time data as well as ratings that neutralized the impact of turnovers, special teams and field position.

Also among the primary elements in play in the newly revised model are Game Splits, the offensive, defensive, special teams, turnover, and field position values that directly relate to the overall margin of victory or defeat in a given game. Sometimes one or more of these factors determines the outcome of the game, exceeding the final score margin. Other times, one or more of these factors has very little relevance to the outcome, and a single unit takes on all the responsibility in the victory.

This week we will take a closer look at the impact offense and defense Game Splits have on individual game outcomes, another glimpse into the way FEI "watches" football.

The first thing to note about offense and defense Game Splits is that the value generated by the best offense and the value generated by the best defense are not equivalent. Remember, this value represents scoring margin, and the offense simply has more of an opportunity to generate scoring margin than the defense. At its best, an offense could score a touchdown on every drive, and if those drives all began from the national average starting field position, the offense will have generated 5.3 points per drive on each of those possessions. (The value of the starting field position is worth most of the other 1.7 points earned on a touchdown drive, and the extra point attempt earns the remaining fractional value.)

A defense performing at its best (barring additional value generated by turnovers) will be forcing three-and-outs on every possession. Given the same example of every opponent possession starting from average starting field position, if the defense kills each drive with a three-and-out and punt, the defense has earned 1.7 points of scoring margin plus another fraction of a point in field position gained for the offense on its next possession. Aside from turnovers, a defense can only earn about 2.5 points per drive playing its best, while an offense can earn more than double that playing its best.

The charts below help illustrate the value contributed to the overall scoring margin of games. Top offenses can run up bigger scoring margins than top defenses.

Note the points on each chart that indicate games in which the value of each unit exceeded the scoring margin value of the game. We noted last week that special teams were the deciding factor in 7.9 percent of games, field position was a deciding factor in 10.1 percent of all games, and turnovers were a deciding factor in 16.4 percent of all games. According to these charts, offensive production was a deciding factor in 35.2 percent of all games and defensive production was a deciding factor in 12.6 percent of all games. In most games, some combination of these factors is needed to decide the game.

All of that said, can we characterize how important offense and defense are? I received a comment on twitter from a reader who was surprised to see that Alabama’s offense generated so much more value last season (+188.6) than its defense (+84.0). Does this really mean that Alabama’s offense was more important than its defense?

I certainly wouldn’t characterize it that way. Instead of highlighting the games in which the scoring margin value produced by the offense and defense exceeded the scoring margin in the game, what if we took a closer look at a particular type of game. Below, the same data from the first set of charts is presented again, this time highlighting games in which the winning team scored a total of 21 points or fewer.

In low-scoring games, offenses generally don’t have as much of an impact as defenses. When the winning score in a game is 21 points or fewer, the defenses of the winning team generated positive value in 91.3 percent of those games. The offenses generated positive value in only 42.4 percent of such low-scoring games.

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Alabama’s defense has been the most consistently dominant in college football in recent years, but the importance of that defensive dominance has varied. Alabama generated positive defensive scoring margin value in 10 of 13 FBS games last year, 12 of 12 FBS games in 2011, 8 of 12 FBS games in 2010, and 13 of 13 FBS games in 2009 -- a total of 86 percent of games played in the last four years. But how often have those defensive performances been the difference between winning and losing?

Last year, it didn’t happen once. In Alabama’s three closest contests, victories over LSU and Georgia and the loss to Texas A&M, the Crimson Tide defense had negative defensive splits. Their sizeable victories in all of their other games required little to no help from the Alabama defense to win the game. In the 2011 championship season, the defensive value generated exceeded the margin of victory only twice (though it almost carried the day in the regular season loss to LSU). Alabama’s defense won zero games for them in 2010. In the 2009 undefeated campaign, Alabama’s defense earned more value than the scoring margin of the game four times.

One thing that isn’t factored in this evaluation is whether the defense could have carried Alabama if the offense wasn’t so efficient itself. I tend to think that Saban’s defenses could probably earn more victories than its offense, if they needed it. The fact that Alabama can dominate defensively and offensively underscores why our projections have gone all in on the Tide for a fourth championship in five years.

We published the FEI projections for the season last week, but they are included below as well. Also see Bill Connelly’s first Varsity Numbers column of the year, detailing the final F/+ ratings and projections for the 2013 season.

On my site, I will be posting win likelihoods and score projections once again this year. The win likelihoods are calculated in the same manner as I have done in the past, as a function of overall FEI rating with an adjustment for home field advantage. The score projections were modified a bit this year based on a regression analysis of offensive and defensive efficiency data. Though the projected winner in terms of both win likelihood and score margin are the same for each game, there is no longer a direct relationship between the two projection elements. Based on the analysis I’ve conducted, this will make for more accurate projected winners and more accurate projected scores.

Win likelihoods and score projections will be based on updated FEI data each week, but I also analyzed the game-by-game accuracy of preseason projections on the season as a whole. Preseason FEI projections alone would have correctly predicted the winner of 69.7 percent of all FBS vs. FBS games over the last four seasons. With an adjustment for home field advantage, preseason FEI projections would have correctly predicted the winner of 71.3 percent of all FBS vs. FBS games since 2009.

FEI 2013 Preseason Projections

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.

Preseason projections are a function of Program FEI ratings, previous-year FEI and garbage time data, previous-year turnover-neutral, special teams-neutral, and field position-neutral FEI, returning starters, recruiting success, and quarterback reliance. As the season progresses and actual 2013 data is collected, the weight given to projected data will be reduced each week until Week 7, at which point it will be eliminated from the rankings entirely. Offensive and defensive FEI ratings will also debut in Week 7.

Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
1 Alabama 0-0 .283 .335 58 11.0
2 Oregon 0-0 .278 .296 48 10.9
3 Stanford 0-0 .253 .187 24 10.1
4 LSU 0-0 .216 .096 5 9.1
5 Florida 0-0 .209 .164 16 9.3
6 Texas 0-0 .208 .221 33 9.4
7 Texas A&M 0-0 .188 .209 30 9.4
8 TCU 0-0 .185 .158 15 8.7
9 Ohio State 0-0 .182 .422 73 10.0
10 Notre Dame 0-0 .182 .179 21 8.9
11 Florida State 0-0 .175 .310 52 9.7
12 Oklahoma State 0-0 .173 .265 38 9.1
13 Georgia 0-0 .172 .199 27 8.6
14 South Carolina 0-0 .169 .269 40 8.9
15 Oklahoma 0-0 .162 .155 14 8.2
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
16 Oregon State 0-0 .157 .168 17 8.8
17 Louisville 0-0 .155 .573 101 10.2
18 Wisconsin 0-0 .152 .333 57 9.2
19 USC 0-0 .149 .213 31 9.4
20 Michigan State 0-0 .147 .286 47 9.2
21 Clemson 0-0 .144 .371 66 9.1
22 Cincinnati 0-0 .136 .643 106 10.2
23 Boise State 0-0 .125 .546 97 9.9
24 Nebraska 0-0 .123 .416 71 9.0
25 Penn State 0-0 .121 .311 53 8.5
26 Northwestern 0-0 .115 .279 44 8.0
27 Michigan 0-0 .104 .195 25 7.0
28 Kansas State 0-0 .101 .223 34 7.8
29 Missouri 0-0 .098 .231 35 7.2
30 Arizona State 0-0 .096 .177 20 7.1
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
31 Virginia Tech 0-0 .087 .305 51 8.1
32 Mississippi 0-0 .087 .111 6 6.9
33 Pittsburgh 0-0 .078 .371 65 7.6
34 Baylor 0-0 .077 .204 29 7.1
35 Iowa 0-0 .074 .275 42 6.7
36 Miami 0-0 .072 .317 54 7.5
37 Northern Illinois 0-0 .068 .716 116 9.8
38 Georgia Tech 0-0 .067 .362 61 7.1
39 BYU 0-0 .064 .250 36 6.6
40 North Carolina 0-0 .063 .362 60 7.6
41 Arizona 0-0 .060 .280 45 7.6
42 Rutgers 0-0 .057 .426 75 7.9
43 Washington 0-0 .052 .134 11 6.5
44 Utah State 0-0 .050 .480 86 8.4
45 Vanderbilt 0-0 .048 .173 18 6.6
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
46 Central Florida 0-0 .046 .383 68 7.3
47 Utah 0-0 .045 .121 7 5.8
48 UCLA 0-0 .044 .085 3 5.7
49 Syracuse 0-0 .043 .297 50 6.7
50 West Virginia 0-0 .039 .186 23 6.2
51 Texas Tech 0-0 .038 .203 28 6.1
52 Mississippi State 0-0 .026 .128 9 5.5
53 Fresno State 0-0 .023 .697 114 8.6
54 Connecticut 0-0 .020 .455 78 6.9
55 Tennessee 0-0 .015 .060 1 5.2
56 Indiana 0-0 .003 .215 32 5.8
57 San Jose State 0-0 .002 .426 76 7.4
58 Tulsa 0-0 -.001 .579 102 7.8
59 Auburn 0-0 -.006 .153 13 5.4
60 Louisiana Monroe 0-0 -.008 .518 92 7.6
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
61 San Diego State 0-0 -.009 .425 74 7.0
62 Iowa State 0-0 -.011 .180 22 4.2
63 Boston College 0-0 -.013 .296 49 5.9
64 Arkansas State 0-0 -.015 .656 108 8.0
65 Toledo 0-0 -.020 .412 70 7.0
66 Bowling Green 0-0 -.021 .748 121 7.9
67 Rice 0-0 -.025 .529 94 7.9
68 Arkansas 0-0 -.027 .072 2 4.2
69 Nevada 0-0 -.027 .363 62 6.0
70 SMU 0-0 -.032 .266 39 5.0
71 Minnesota 0-0 -.032 .274 41 4.7
72 Ohio 0-0 -.034 .600 104 8.2
73 Houston 0-0 -.038 .420 72 5.5
74 Ball State 0-0 -.039 .738 120 7.9
75 California 0-0 -.040 .093 4 4.1
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
76 Virginia 0-0 -.040 .276 43 4.5
77 South Florida 0-0 -.040 .353 59 5.0
78 North Carolina State 0-0 -.041 .478 85 5.9
79 Louisiana Tech 0-0 -.043 .829 125 7.9
80 Purdue 0-0 -.046 .152 12 3.5
81 Temple 0-0 -.047 .322 55 5.5
82 Navy 0-0 -.053 .491 87 6.1
83 Louisiana Lafayette 0-0 -.054 .668 111 7.0
84 Western Kentucky 0-0 -.057 .772 123 6.9
85 East Carolina 0-0 -.059 .709 115 6.7
86 Kent State 0-0 -.059 .388 69 5.9
87 Kentucky 0-0 -.060 .132 10 3.7
88 Maryland 0-0 -.067 .382 67 4.5
89 Wake Forest 0-0 -.067 .365 63 4.6
90 Troy 0-0 -.071 .649 107 6.1
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
91 Middle Tennessee 0-0 -.071 .659 109 6.9
92 Duke 0-0 -.073 .566 99 4.9
93 Marshall 0-0 -.084 .683 112 6.5
94 Central Michigan 0-0 -.087 .660 110 5.9
95 Buffalo 0-0 -.088 .475 83 5.7
96 North Texas 0-0 -.097 .547 98 5.5
97 Southern Mississippi 0-0 -.103 .504 90 4.7
98 Wyoming 0-0 -.105 .445 77 5.8
99 Western Michigan 0-0 -.106 .370 64 4.7
100 South Alabama 0-0 -.108 .796 124 5.5
101 Florida International 0-0 -.116 .603 105 5.1
102 UNLV 0-0 -.121 .737 119 4.8
103 UAB 0-0 -.123 .465 81 4.7
104 Air Force 0-0 -.123 .528 93 4.9
105 Illinois 0-0 -.128 .256 37 2.7
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
106 Texas State 0-0 -.132 .755 122 5.3
107 UTSA 0-0 -.132 .594 103 4.3
108 Colorado State 0-0 -.135 .284 46 5.0
109 UTEP 0-0 -.138 .543 96 4.8
110 Army 0-0 -.143 .573 100 4.3
111 Hawaii 0-0 -.145 .462 80 3.0
112 Florida Atlantic 0-0 -.146 .689 113 4.1
113 Memphis 0-0 -.150 .499 88 3.2
114 Colorado 0-0 -.159 .198 26 2.3
115 Washington State 0-0 -.161 .121 8 2.5
116 Kansas 0-0 -.173 .175 19 2.0
117 Eastern Michigan 0-0 -.178 .505 91 3.1
118 Tulane 0-0 -.195 .732 117 3.4
119 Akron 0-0 -.199 .533 95 3.3
120 Miami (OH) 0-0 -.202 .735 118 2.8
Rank Team FBS
W-L
FEI SOS SOS
Rk
FBS
MW
121 New Mexico State 0-0 -.219 .476 84 3.6
122 New Mexico 0-0 -.223 .499 89 2.5
123 Georgia State 0-0 -.223 .327 56 2.3
124 Massachusetts 0-0 -.252 .471 82 2.5
125 Idaho 0-0 -.265 .462 79 2.2

Posted by: Brian Fremeau on 28 Aug 2013

5 comments, Last at 30 Aug 2013, 6:12pm by IrishBarrister

Comments

1
by grady graddy (not verified) :: Thu, 08/29/2013 - 12:09pm

My knee hurts just looking at the picture on the front page that links to this article.

2
by collapsing pocket (not verified) :: Thu, 08/29/2013 - 1:01pm

Did you have to pick a photo of one of the most gruesome knee injuries ever for this article?

4
by Rivers McCown :: Fri, 08/30/2013 - 10:26am

Heh. Sorry, that's just the only photos of Mosley the photo service had and I try to make sure I get one of every highly-rated prospect as we go through the season so we have some on their player pages when they get picked.

3
by Will :: Thu, 08/29/2013 - 7:29pm

"In low-scoring games, offenses generally don’t have as much of an impact as defenses."

Isn't that equivalent of saying, "in games where offenses are not playing well, defense is more important"?

Will

5
by IrishBarrister :: Fri, 08/30/2013 - 6:12pm

Brian: I am a little confused by how much you are allocating the improved field position to the defense.

For example, Team A starts from their own 25 yard line, goes three-and-out, and punts leaving Team B on their own 35 yard line. That, by my calculations, is a 3.7 point swing (1.7 for Team A's field position, and 2.0 for Team B's new field position). Or we can say that the defense only gets credit the improvement in field position from average (i.e., ~25 yard line, 1.7 points). In the above example then, the defense earns a 2.0 point swing.

But you credit the defense for 2.5, however, leaving me wondering what I might be missing here.