There are many factors that affect the game state of an NFL game and have a direct influence on the Game-Winning Chance (GWC). Football is different, in this way, from many other sports. Each down represents a unique situation that is defined by score, ball position, yards-to-first, clock, timeouts and the match up of the teams’ strengths and weaknesses. It is like a book of problems where each turn of the page reveals a new game state we have literally never seen before. We may be able to reference a similar situation that has occurred in the past, but it will not properly account for the astronomical number of combinations that define the play at hand.
The GWC of many free-flowing games such as soccer, hockey, and basketball are largely defined by possession, score, clock, and match up. This is similar to football but without the added layer of discrete downs that have the additional variables of ball position and yards-to-first. Consider baseball, which has been a Sabermetrician’s dream since Bill James began publishing his “Baseball Abstract” in the 1970s. The way teams think about line-ups, shifting, pitching rotations, and on-base percentage has revolutionized that game. Despite all of its beautiful complexity, baseball is missing two key ingredients that distinguish it from football: the running clock and variable scoring increments. In baseball, you are generally trying to produce runs and to keep your opponent from producing runs. The utility of those runs may change as a function of the game state, but typically teams will be compelled to improve or protect their score at all phases of the game. Football is different in that points can be scored in groups of 1, 2, 3, or 6, and the impact of that scoring on GWC can change dramatically as a function of the clock and the score. There are times when a field goal is worthless or a touchdown is too much. And as we have seen this season, it can even be correct to reject scoring voluntarily or, conversely, to allow your opponent to score.
As the Pittsburgh Steelers were putting the finishing touches on an impressive second-half comeback against the Colts yesterday, they faced a fourth-and-1 from their own 44-yard line. With a 28-24 lead and only 2:18 separating him from a divisional title, Mike Tomlin decided to do what most NFL coaches would do; he punted the ball. This choice is more complex than it may appear on the surface. When the goal is to improve GWC, every important variable that defines the game state must be considered. Ultimately, the Steelers were able to squelch a game-winning drive by Philip Rivers and the Colts, but according to a detailed simulation by the EdjSports model, they would have won more often, on average, by attempting a first down rather than a punt. At -4.5% GWC, this was one of the largest fourth-down errors of the week and likely went unnoticed as the Steelers were celebrating their victory.
While this error is significant, it is certainly nowhere near the worst we have seen this season. That is reserved for Kliff Kingsbury at -21% GWC. However, this decision by Tomlin serves as an excellent example of the complexity of football analytics and how changing the game state impacts the correct choice.
Impact of Game State on a Critical Fourth Down Decision
- Steelers lead 28-24 with 2:18 remaining in the game, fourth-and-1 on their own 44-yard line, Colts have no timeouts
GWC Difference of Punt vs. Go When Adjusting for Score Only:
GWC Difference of Punt vs. Go When Adjusting for Yards-to-First Only:
GWC Difference of Punt vs. Go When Adjusting for Game Clock Only:
The simulation is accounting for some fascinating nuance. When leading by 1, it becomes far more correct to attempt the first down than the actual case. This may seem counter-intuitive, but I suspect the model is picking up on the fact that when the Steelers fail on fourth down, the Colts will not necessarily burn all of the clock to get a field goal. After the punt, the Colts will only need a field goal, of course, but now they are more likely to milk the entire clock in doing so. Surprisingly, the model also slightly favors going for it even on fourth-and-3. This illustrates the importance of retaining possession and keeping the ball away from the opposing offense. Finally, it may seem odd that the GWC difference actually drops when adjusting the clock from 1:00 to 0:20, but this is simply a function of the overall GWC approaching 100% for both choices.
It is illuminating to see how small changes in game state variables can affect whole percentage points of GWC. As we often say, just 6% of GWC per game is an expected difference of an entire game over a 16-game season and often the difference between making the playoffs or not.