Writers of Pro Football Prospectus 2008

17 Sep 2014

FEI Week 3: Bulldogs Bog Down

by Brian Fremeau

I don’t get an opportunity to watch every big game as it unfolds. I didn’t see much of South Carolina’s 38-35 victory over Georgia on Saturday. I hadn't been aware of the first-down marker drama that unfolded in the waning moments of that victory until I caught highlights later on that evening. And until I poured over the box score and drive summary on Saturday night, I hadn’t realized Georgia had completely blown its final offensive possession of the game to set up that drama.

With just over five minutes left in regulation, South Carolina clung to a three-point lead deep in their own territory. On third-and-10 from their own 14-yard line, South Carolina quarterback Dylan Thompson threw an interception into the hands of Georgia cornerback Damian Swann, who weaved his way toward the end zone before being corralled inside the 10-yard line. A penalty on the Gamecocks gave Georgia a first-and-goal situation on the South Carolina 4-yard line.

I calculate the value of turnovers as a function of the impact of killing an opponent offensive drive plus the value added based on the resulting field position. This particular interception killed a drive that would likely have ended with a punt had the pass merely fallen incomplete, so not much value was gained by that part of the play. But an interception that sets up the offense on the doorstep of the end zone is significant. Swann’s play added 4.9 points of scoring value for Georgia. Had the Bulldogs been able to capitalize with a touchdown, most of the value gained would have belonged to Swann and the defense.

In terms of possession value, Georgia had already “taken the lead” on the play. To fail to score a touchdown, or to fail to score at all would be equivalent to taking points off the board.

How valuable is a possession that starts at the opponent’s 4-yard line? From 2007 to 2012, there were 79 total drives in FBS vs. FBS games in which an offense started a drive from that position on the field. The offenses scored 60 touchdowns on those drives (75.9 percent). Four of those drives resulted in a turnover, one on a turnover on downs, and three resulted in time running out at the end of a half. The other 11 resulted in a field-goal attempt, nine of which were successful. The field-position value of the opponent’s 4-yard line is 5.8 points, according to my data.

On non-garbage possessions since 2007, offenses have scored points on 92.6 percent of drives that began inside the opponent’s 5-yard line. Offenses scored touchdowns on 60.1 percent of drives started at or inside the opponent’s 20-yard line. In the same span leading up to the South Carolina game, Georgia started 20 drives in the red zone and scored a touchdown on 16 of them (80 percent). They scored a touchdown on all six of their non-garbage drives started at or inside the opponent’s 5-yard line from 2007 to 2013.

Georgia’s offense was probably going to score against South Carolina. But they did not. Bulldogs quarterback Hutson Mason was called for intentional grounding and a loss of 10 yards on first down, Todd Gurley was held up for a 3-yard gain on second down, and Mason’s third-down pass was batted down incomplete. The offense lost 7 yards on the sequence, an offensive possession value of minus-3.3 points.

How much is a field-goal attempt worth from the opponent’s 11-yard line? College kickers are successful on approximately 85 percent of attempts from that distance since 2007. A successful kick puts three points on the scoreboard, but only 0.5 of those points are earned by the kicker from that yard line. The other 2.5 points were earned by the units that set up the kick. In this case, Swann’s interception set up 5.8 points of scoring value, and the offense lost 3.3 points. A successful kick would tie the game. An unsuccessful kick would blow the remaining 2.5 points of value the defense had generated.

You know how this story ends. Georgia kicker Marshall Morgan pushed the field-goal attempt just right of the goalpost, South Carolina took possession, and the Gamecocks ran out the clock.

Georgia’s net field position-value advantage for the game was 9.4 points. Their net turnover value generated for the game was 8.7 points. Only four teams last season had advantages at least that large in field position and turnovers and still lost the game. Oddly, three of those four games happened on the same day.

2013 Games In Which Teams Were At Least +9.4 In Field Position and +8.7 In Turnovers And Lost
Date Team NG Final Final Opponent NFP NTO
10/12 Kansas 17-27 17-27 TCU 10.6 13.8
10/12 Virginia 26-27 26-27 Maryland 10.8 12.0
10/12 Iowa State 35-42 35-42 Texas Tech 19.2 11.5
10/19 Memphis 23-34 29-34 SMU 20.1 13.1

Beginning this week, game splits data for all FBS vs. FBS games is available on my site, breaking down the scoring value contributed by the offense, defense, and special teams units as well as the field-position and turnover values generated or lost. I’ve also added available yards data for each game, and the page is now coded for links directly to team data. Georgia’s game splits are here and South Carolina’s are here.

Beginning this week I have also updated the offense, defense, and field position pages here at FO for 2014 unadjusted data. Opponent-adjusted offense and defense data will debut after Week 7.

FEI 2014 Week 3 Ratings

The Fremeau Efficiency Index (FEI) is a college football rating system based on opponent-adjusted drive efficiency. Nearly 20,000 possessions are contested annually in FBS vs. FBS games. First-half clock-kills and end-of-game garbage drives and scores are filtered out. Game Efficiency (GE) is a function of the starting field position and outcome of non-garbage possessions. Opponent adjustments are calculated with special emphasis placed on quality performances against good teams, win or lose.

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 all regular season games scheduled. A multifaceted approach to measuring schedule strength is available here.

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 total games a team with the given FEI rating should expect to win against the remaining opponents on its schedule.

These ratings are partially influenced by preseason projections, 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 2014 data continues to be collected, the weight given to projection 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 LW GE GE
Rk
SOS SOS
Rk
FBS
MW
FBS
RMW
1 Oregon 2-0 .314 1 .321 13 .128 35 9.6 7.8
2 Florida State 1-0 .307 2 .059 48 .172 49 9.7 8.9
3 Missouri 2-0 .255 9 .304 15 .175 50 9.2 7.3
4 Stanford 1-1 .253 4 .210 22 .034 1 7.8 6.2
5 LSU 2-0 .247 7 .213 20 .085 22 8.3 6.6
6 USC 2-1 .243 3 .151 27 .089 25 9.2 7.1
7 Mississippi 3-0 .235 11 .479 2 .113 30 8.4 5.6
8 Alabama 3-0 .231 5 .368 7 .108 28 8.2 5.4
9 Georgia 1-1 .229 6 .083 38 .139 41 8.5 7.3
10 Oklahoma 3-0 .226 8 .440 6 .313 72 10.2 7.3
11 Texas A&M 2-0 .224 12 .333 10 .049 9 7.3 5.8
12 Auburn 2-0 .218 15 .333 11 .035 2 6.8 4.9
Rank Team FBS
W-L
FEI LW GE GE
Rk
SOS SOS
Rk
FBS
MW
FBS
RMW
13 Notre Dame 3-0 .215 10 .351 8 .048 7 8.4 5.6
14 Michigan State 0-1 .210 14 -.127 95 .132 38 8.6 8.4
15 South Carolina 2-1 .203 18 -.020 66 .110 29 7.6 5.8
16 Virginia Tech 1-1 .193 13 .033 54 .212 53 8.3 7.0
17 Ohio State 2-1 .184 20 .202 23 .264 64 9.2 6.9
18 BYU 3-0 .183 16 .213 19 .546 106 9.3 6.8
19 Oklahoma State 1-1 .180 19 .075 41 .082 21 7.4 6.3
20 Wisconsin 0-1 .179 21 -.041 73 .303 71 8.7 8.4
21 Kansas State 1-0 .176 25 .048 49 .148 44 7.6 6.9
22 Clemson 0-1 .174 27 -.173 102 .073 17 7.1 6.9
23 UCLA 3-0 .172 24 .065 44 .073 16 7.5 5.2
24 Baylor 2-0 .171 23 .444 4 .243 58 8.1 6.1
25 Louisville 1-1 .167 22 .047 51 .114 31 7.4 6.0

Posted by: Brian Fremeau on 17 Sep 2014

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