By Andrew Mooney
A couple weeks ago, I discussed the implications of one of the NFL’s recent rule changes, namely the movement of kickoffs from the 30-yard line to the 35. Though we don’t have quite as much evidence for it yet, I’m now going to examine the preliminary effects of another new rule: the NFL’s amended overtime procedure.
Seeking to reduce the influence of luck—the result of a coin flip—on the result of overtime games, the NFL no longer follows the traditional “sudden death” format. The team that receives the ball first can still end the game on its first possession, but only with a touchdown; if it makes a field goal, the opposing team gets one possession to match or exceed it. If an overtime period begins with matching field goals, the rules revert back to sudden death, with the first team to score winning the game.
Analysis conducted by Advanced NFL Stats reveals that, under the old system, the team that won the overtime coin toss ultimately won the game 60 percent of the time. Given the rate at which teams score touchdowns and field goals, the same analysis predicted that this rate would fall to 56 percent with the new rules, assuming equal teams. This is an improvement, but still not enough to totally even out the odds. Though we’re not yet through the first season with the overtime rule change, I thought it would be interesting to look at the outcomes we’ve seen so far to see how closely the early returns on the new rules match reality.
There have been 17 overtime games this year, through 12 weeks of play—a very small sample size compared to the hundreds of overtime games played under the old rules. The teams who have received the ball first have won 11 of these 17, lost five, and tied one, for a winning percentage of 0.676. This rate seems unsustainably high—an increase from before the rule change—and likely to come down in the ensuing weeks and seasons. Still, it appears the team that wins the coin toss continues to possess a marked advantage.
Historically, about 75 percent of overtime games have been decided by field goals, while the other quarter has been sealed with touchdowns. This year’s contests have mostly mirrored this trend; ten games have been won by field goals, three by touchdowns, and three by turnovers, a new outcome under the current rules.
Other overtime notes:
-Eight out of the 17 games (47 percent) have been decided in the first two possessions, as compared to 18 of 32 (56 percent) over the previous two seasons (2010-11).
-Teams with the better record as of Week 12 won 11 of the 17 games.
-The average time elapsed in these overtime periods was 7:28, with an average of 2.88 possessions. The previous two years, the average time elapsed was 6:47, coming on an average of 2.81 possessions—very similar to the numbers under the new rules.
-The home team won eight of the 17 games (47 percent) this year, again close to the results from the last two seasons, in which the home team won 14 of 32 games (44 percent).
Again, the data from this season and the previous two do not represent a large sample size, so the analysis doesn’t lend itself to any robust conclusions. However, it does paint a (very) preliminary picture of a trend that will be of interest over the next few seasons.