by Brian Fremeau
Last weekend’s “game of the century” did not disappoint. LSU and Alabama may not have faced off in a consensus No. 1 vs. No. 2 matchup, but the stature of the programs and the spectacle of the event was the kind of heavyweight battle college football fans want to see more often. And unlike many of the most recent iterations of this particular rivalry, both teams were equipped to take the other’s best swing and counterpunch effectively. Both teams were capable of putting together explosive and efficient offensive attacks against one another. Both teams were stocked with elite talent. In nearly every way, the game delivered on its lofty expectations.
One of the few things the game failed to deliver was back-and-forth scoring. Alabama coughed up the ball on its first possession, and LSU immediately answered with a long touchdown drive. Alabama had a special teams snafu on its next possession and LSU took advantage of the short field position to open up a 10-point lead. The Tigers opened up a 20-point lead at the half, and fended off the Crimson Tide comeback throughout the second half. Alabama clawed back to within five points with under six minutes left in the fourth quarter, but LSU answered with what felt very much like a dagger — a 75-yard touchdown drive to effectively end the game, up 46-34 with under two minutes left.
When I watch college football, I often make mental notes as to how the possession efficiency metrics I assemble may be measuring what I’m seeing. When LSU scored late in the fourth quarter, I didn’t expect an answer from Alabama, and had falsely assumed that garbage time was about to commence. Instead, Alabama torched LSU for an 85-yard touchdown pass down the sideline on the first play of its ensuing possession, suddenly opening up a window for the Tide to possibly steal victory from the jaws of defeat. LSU did safely corral the onside kick attempt and kneel out the win. But instead of a victory by double-digits, the possession efficiency story of the game will tell a bit tighter tale.
That 85-yard play has me thinking about the limitations of possession efficiency. More specifically, it serves as a reminder that I built FEI to not care about when the non-garbage possessions take place or in what sequence. My personal perspective watching the game was of one team jumping all over the other early. The drama came with LSU answering the bell late while Alabama chipped away at a big lead. But if the order of scoring drives and failed drives was shaken up, I would probably have an entirely different narrative to tell about the game, even though the underlying stats would be the same.
Imagine if Alabama had opened the game with an 85-yard touchdown pass instead of concluding it with one. What if they had fumbled late in the game while clinging to a lead, instead of fumbling early to allow LSU to seize on that opportunity? I, and I’d guess many others, would have a very different feeling about the relative merits of the two teams in those scenarios. FEI, however, doesn’t care about the order of those events. My head tells me that’s the right approach, but my gut wants me to give it more scrutiny. I’m not specifically talking about quantifying momentum (and likely finding no evidence of its statistical validity), but does this game suggest there is more to be explored with game states? Is a five-point victory in a game the winner controlled from the jump really the same as a five-point victory in a back-and-forth seesaw battle or a five-point victory in a big comeback?
One way to approach that question is to isolate only a portion of the game. I ran the FEI ratings formula with only first-half possession data as an input. Instead of LSU defeating Alabama 46-41 over the course of 26 full-game non-garbage possessions, what if our input was LSU’s “defeat” of Alabama 33-13 over the course of 16 first-half non-garbage possessions? And instead of comparing LSU’s per-possession performance in the game against Alabama’s overall opponent profile, what if we only compared LSU’s first-half performance against Alabama’s first-half performances for the year?
If we do this exercise for all teams, the resulting FEI ratings do differ from the overall FEI ratings, as one would expect when only a portion of each team’s data is included. Ohio State is No. 1 in FEI overall, and No. 1 in first-half FEI as well. LSU slides from No. 4 overall to No. 2 in first-half FEI. Alabama slides from No. 2 overall to No. 7. The first-half FEI top-30 is included in the table below.
The chart provides a bit of perspective on how teams have or have not performed consistently from half to half. Many of the teams on the list have a markedly better first-half rating than an overall rating. Ohio State, for instance, has been so dominant out of the gate that it makes me wonder if their full-game FEI is actually underrating them. Or perhaps the more limited data of first-half stats can exaggerate efficiency. Clemson and Wisconsin are two other examples of teams that have racked up several dominant victories, and the first-half FEI ratings likely boost the apparent dominance of an overall game by isolating a dominant stretch of limited possessions.
Navy jumps off the chart at No. 5 in first-half FEI. The Midshipmen are 6-1 against FBS opponents and rank No. 14 in overall FEI. But Navy is undefeated in first-half play — they led Memphis 20-13 at the half before losing 35-23. And of the 16 touchdowns Navy has surrendered this year against FBS opponents, only five were scored in the first half.
A much more extensive review this off-season of first-half FEI data, and specifically its predictive qualities, will need to be done to determine its value. But my instinct is that there is more to the sequence of possession efficiency to explore than I have to date. At the very least, new slices of data offer new perspectives on team performances as potentially predictive trends or otherwise.
2019 FEI Ratings (through Week 11)
The Fremeau Efficiency Index (FEI) is a college football rating system based on opponent-adjusted possession efficiency, representing the per possession scoring advantage a team would be expected to have on a neutral field against an average opponent. Unadjusted possession efficiency (PE) is calculated as a function of offensive, defensive, and special teams game splits. Schedule strength is represented by each team’s average per possession opponent adjustment (OA). Opponent-adjusted offense ratings (OFEI), opponent-adjusted defense ratings (DFEI), and opponent-adjusted special teams ratings (SFEI) are calculated in a similar manner as overall FEI ratings. Team records against all FBS opponents (W-L) and against opponents ranked in the FEI top 10 (v10), top 20 (v20), top 30 (v30), top 40 (v40), and top 50 (v50) are also provided.
Ratings and supporting data are calculated from the results of non-garbage possessions in FBS vs. FBS games.