Writers of Pro Football Prospectus 2008

14 Oct 2015

FEI Week 6: Possession Wins

by Brian Fremeau

The showdown between 4-1 Michigan and 5-0 Northwestern in Ann Arbor last weekend was expected by many to be a low-scoring, 60-minute slugfest, but the Wolverines had other ideas. Michigan returned the opening kickoff for a touchdown, forced a three-and-out, scored again on a 59-yard touchdown drive, held Northwestern to a failed field goal attempt, scored again on a 75-yard touchdown drive, and forced another three-and-out. The score was 21-0 in favor of Michigan at the conclusion of that six-possession sequence. Northwestern never found its footing through the rest of the game, trailed 31-0 through 18 non-garbage possessions, and lost by a final score of 38-0. It was the Wolverines' third straight shutout and fourth victory of the season in which they generated positive scoring value in all three phases of the game.

I was reminded recently of the origins of the FEI ratings and my first instincts of what kind of data I wanted to collect to measure baseline efficiency in college football. Way back in 2003, I was originally trying to quantify momentum, an intangible I tried to make tangible by defining it as a team's ability to string together consecutive successful possessions. The opening sequence of the Michigan game is a perfect example of what I was after -- six possessions featuring three scores and three stops in favor of the Wolverines before Northwestern finally won a possession of their own by forcing a punt on the next Michigan drive.

Twelve years ago, I filled a notebook with possession win sequences from every FBS game of the 2003 season, and didn't record any other information about the drives at all. I didn't care where the drives started or ended, and I didn't care about the actual outcome of the drives. My notes that year were devoted exclusively to recording whether a team won or lost each possession based on scores and stops, and my efficiency calculations centered on the sequencing of those groups of possession wins and losses.

notebook

Possession win sequence notebook from 2003, the origins of the FEI ratings.

The following year, I shifted my focus away from this rudimentary definition of possession success to the more sophisticated approach I take today in evaluating drive success as a function of field position value. I'm reviving the original idea this week as a supplement to the FEI ratings.

I'll define basic possession wins and losses today as I did then. Touchdowns and field goals are recorded as possession wins for the team with the ball and possession losses for the opponent. All other results are recorded as possession losses for the team with the ball and possession wins for the opponent. The possession win percentage (PWP) leaders in Table 1 have the highest percentage of possession wins per non-garbage game possession through the first six weeks of this season.

Possession Win Percentage Leaders Through Week 6
Rank Team FBS
W-L
Po PW PL PWP
1 Baylor 4-0 84 62 22 .738
2 Michigan 5-1 125 85 40 .680
3 Utah 5-0 113 73 40 .646
4 LSU 5-0 104 67 37 .644
5 Boise State 4-1 129 83 46 .643
6 Houston 4-0 97 62 35 .639
7 Toledo 5-0 113 71 42 .628
8 Texas A&M 5-0 120 75 45 .625
9 Florida State 5-0 108 67 41 .620
10 Stanford 4-1 97 60 37 .619

Michigan ranks No. 2 in the nation this week in this measure of possession success, having won 68 percent of all non-garbage possessions it has played this year. How about the sequencing of possession wins? The six consecutive possession wins in a sequence to start the game against Northwestern buried the Wildcats early in the game. In the second quarter, Michigan tallied three consecutive possession wins in another sequence -- an interception (stop), which was returned for a touchdown (score), followed by a forced three-and-out (stop). To start the third quarter against Northwestern, Michigan forced a punt (stop), netted a field goal on the ensuing possession (score), and forced another punt on the next drive (stop) -- another sequence of three possession wins for the Wolverines.

Northwestern was shut out and never managed to pair even two consecutive possession wins together in the game. The Wolverines didn't allow a pair of consecutive possession wins against UNLV, BYU, or Maryland, either. Against BYU, Michigan actually tallied a 12-possession win sequence of its own (seven stops and five scores without interruption, spanning from the first quarter into the third quarter) while building a 31-0 lead over the Cougars. Michigan has allowed only one sequence all year of at least three consecutive opponent possession wins and that came six weeks ago –- Utah tallied an interception (stop), interception return touchdown (score), and forced a turnover on downs (stop) in a fourth-quarter sequence on September 3 against the Wolverines.

We can divide the total number of possession wins for each team by its total number of possession win sequences to calculate the team's possession win average (PWA). Likewise, the number of possession losses divided by the number of possession loss sequences is a team's possession loss average (PLA). The leaders through the first six weeks of the season in these categories are listed in the following tables.


Possession Win Average Leaders Through Week 6
Possession Loss Average Leaders Through Week 6
Rank Team FBS
W-L
PWA Rank Team FBS
W-L
PLA
1 Baylor 4-0 2.95 1 Michigan 5-1 1.18
2 Boise State 4-1 2.68 2 Baylor 4-0 1.22
3 Utah State 2-2 2.67 3 Boston College 1-3 1.36
4 Houston 4-0 2.48 4 Duke 4-1 1.39
5 Arizona 3-2 2.48 5 Toledo 5-0 1.40
6 Ohio State 6-0 2.40 6 North Carolina 2-1 1.41
7 Mississippi 4-1 2.40 7 Stanford 4-1 1.42
8 LSU 5-0 2.39 9 Utah 5-0 1.43
9 Notre Dame 5-1 2.39 8 Clemson 4-0 1.43
10 Utah 5-0 2.35 10 Missouri 3-2 1.44

If we associate possession win sequences with momentum, we could say that the PWA leaders are the teams that most successfully generate momentum, and the PLA leaders are the teams that most successfully thwart momentum. Is there a magic number of possession wins in a sequence that guarantee victory in a game? Not necessarily. South Carolina trailed Kentucky by a halftime score of 24-7 back on September 12th, a first half that concluded with eight straight possession wins for the Wildcats. The Gamecocks topped that with a nine-possession win sequence in the second half to pull to within two points (punt, field goal, punt, field goal, punt, field goal, punt, touchdown, punt). South Carolina's rally fell short on the final possession of the game, however, with an interception for Kentucky that sealed the victory.

The longest sequence of possession wins so far this season was tallied by Baylor against Kansas last weekend. After trading touchdowns to start the game, the Bears ran off 14 straight possession wins to build a 52-7 first-half lead over the Jayhawks. There have been six instances so far this season in which a team tallied at least 10 consecutive possession wins in a single sequence, and all six instances led to victory for that team. 94 percent of all eight-possession win sequences have been tallied by teams that went on to win. 93 percent of all six-possession win sequences have been tallied by teams that went on to win the game. 79 percent of all four-possession win sequences have been tallied by teams that went on to win the game.

I'm categorizing this last group as "multiple possession win sequences" because four-possession win sequences require at least two stops and two scores in a given sequence to qualify. 32.3 percent of Boise State's possession win sequences are of this variety so far this year, the highest rate nationally of generating multiple possession win sequences. Six teams have yet to allow a multiple possession win sequence. The national leaders in generating multiple possession win sequences (MWP) and allowing such sequences (MLP) through the first six weeks of the season are listed in the tables below.


Multiple Win Percentage Leaders Through Week 6
Multiple Loss Percentage Leaders Through Week 6
Rank Team FBS
W-L
MWP Rank Team FBS
W-L
MLP
1 Boise State 4-1 .323 1 Baylor 4-0 .000
2 Appalachian State 3-1 .273 1 Michigan 5-1 .000
3 Arizona 3-2 .261 1 Oklahoma State 5-0 .000
4 Tulsa 3-2 .235 1 Stanford 4-1 .000
5 Mississippi 4-1 .233 1 USC 3-2 .000
7 North Carolina 2-1 .222 1 Utah 5-0 .000
6 Notre Dame 5-1 .222 7 Marshall 4-1 .022
8 UCLA 4-1 .219 8 Boston College 1-3 .024
9 LSU 5-0 .214 9 Missouri 3-2 .026
10 Virginia Tech 2-3 .207 10 Duke 4-1 .026

The possession win data for all 128 teams can be found here and will be updated weekly throughout the remainder of the season. Michigan will put its impressive possession win success to the test once again this weekend against undefeated rival Michigan State.

Degree of Difficulty Through Week 6

The DOD rankings are based on current FEI ratings, but instead of measuring efficiency against schedule, DOD measures record against schedule. How difficult would it be for an elite team (two standard deviations better than average) to play a given team's schedule to date and achieve that team's record?

My hypothesis is that the College Football Playoff selection committee is likely to value and reward something akin to DOD through their process and deliberations. Last year, the top four teams in DOD before the bowls were also the four teams selected for the playoff, and TCU and Baylor ranked fifth and sixth, respectively.

As of this week, the following teams have the most impressive records and have accomplished the most to date.

Degree of Difficulty through Week 6
Rank Team W-L DOD
1 Clemson 4-0 .586
2 Utah 5-0 .590
3 Texas A&M 5-0 .590
4 Florida 6-0 .606
5 TCU 5-0 .608
6 LSU 5-0 .669
7 Oklahoma State 5-0 .695
8 Ohio State 6-0 .752
9 Iowa 5-0 .792
10 Houston 4-0 .809

FEI Week 6 Ratings

The Fremeau Efficiency Index (FEI) is a college football rating system based on opponent-adjusted drive efficiency. Approximately 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. Unadjusted game efficiency (GE) is a measure of net success on non-garbage possessions, and opponent adjustments are calculated with special emphasis placed on quality performances against good teams, win or lose. Other definitions:

  • SOS: Strength of Schedule, measured as the likelihood of an elite team going undefeated against the given team's regular season schedule. Schedule strength data based on FEI ratings and calculated across other dimensions can be explored in this interactive visualization.
  • FBS MW: Mean Wins, the average number of games a team with the given FEI rating would be expected to win against its regular season schedule of FBS opponents.
  • FBS RMW: Remaining Mean Wins, the average number of games a team with the given FEI rating would be expected to win against the remainder of its regular season schedule of FBS opponents.

Preseason projections are a function of program strength and trajectory as well as transition factors including returning starters and recruiting success. The weight given to preseason projections is reduced in the FEI formula over the first half of the season until it is eliminated entirely following the results of Week 7. Preseason projection data receives 15 percent of the weight in this week's ratings. Ratings for all FBS teams can be found here.

Rank Team FBS
W-L
FEI LW GE GE
Rk
SOS SOS
Rk
FBS
MW
FBS
RMW
1 Clemson 4-0 .274 2 .194 14 .397 76 10.3 6.7
2 Alabama 5-1 .266 1 .229 9 .148 25 9.2 3.7
3 LSU 5-0 .238 6 .236 7 .099 9 8.8 4.2
4 Baylor 4-0 .228 3 .476 1 .180 33 9.1 5.3
5 Utah 5-0 .222 9 .235 8 .236 47 10.0 5.7
6 Texas A&M 5-0 .221 5 .240 6 .118 15 8.5 4.2
7 Stanford 4-1 .218 4 .215 12 .221 42 9.9 5.8
8 Notre Dame 5-1 .218 8 .188 16 .103 10 9.5 4.6
9 TCU 5-0 .212 10 .161 21 .181 36 8.7 4.4
10 Ohio State 6-0 .206 7 .224 10 .380 73 10.3 4.8
11 Michigan 5-1 .192 22 .302 2 .210 40 9.5 4.7
12 Michigan State 6-0 .183 12 .154 22 .286 57 9.8 4.2
13 Oklahoma State 5-0 .182 20 .133 29 .276 54 8.5 4.3
14 UCLA 4-1 .180 16 .163 20 .130 19 8.9 4.6
15 Boise State 4-1 .173 26 .244 5 .637 115 9.9 5.7
Rank Team FBS
W-L
FEI LW GE GE
Rk
SOS SOS
Rk
FBS
MW
FBS
RMW
16 USC 3-2 .173 11 .246 4 .133 20 8.1 4.4
17 Oklahoma 4-1 .170 15 .141 27 .126 17 8.5 4.4
18 Florida 6-0 .163 31 .185 17 .233 45 9.0 4.2
19 Mississippi 4-1 .161 18 .152 23 .082 5 7.0 3.5
20 Arizona State 3-2 .153 17 .032 54 .128 18 7.1 3.9
21 Kansas State 2-2 .152 21 .048 47 .210 41 7.7 5.2
22 Mississippi State 3-2 .150 24 .101 39 .143 23 7.1 4.0
23 Florida State 5-0 .144 19 .209 13 .177 30 8.1 3.7
24 Northwestern 4-1 .143 13 .047 48 .222 43 7.5 4.6
25 Tennessee 2-3 .141 32 .045 51 .157 27 7.6 4.5
26 California 4-1 .133 51 .076 43 .080 3 6.5 3.1
27 Navy 3-1 .131 39 .133 30 .361 71 8.7 5.9
28 North Carolina 2-1 .128 25 .143 26 .506 99 7.4 5.1
29 Duke 4-1 .119 27 .127 31 .450 89 8.0 4.0
30 Iowa 5-0 .117 28 .148 24 .448 88 8.2 4.2

Posted by: Brian Fremeau on 14 Oct 2015

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