By now every NFL fan knows what happened in Monday night's Lions-Seahawks game.
With 1:51 left to play, Detroit trailed by three points and faced a third-and-1 from the Seattle 11. As receiver Calvin Johnson tried to stretch across the goal line, safety Kam Chancellor punched the ball loose, sending it bouncing into the end zone. As the ball fluttered toward the back of the end zone, Seattle linebacker K.J. Wright tapped the ball, accelerating it out of play and assuring Seattle a touchback. We now know that this was a case of illegal batting, and had the referees called the penalty, Detroit would have regained possession inside the 1-yard line, half the distance from the spot of the fumble.
And while it's impossible to know for certain which team would have won the game had things gone differently, we can make some good estimates about each team's chances using our win probability model.
There's little doubt Chancellor's amazing play saved a touchdown and prevented the Seahawks from falling behind by four points with less than two minutes remaining. Here's the breakdown:
• A Detroit touchdown leaves Seattle down by four with 1:45 to play, giving the Seahawks a 15.7 percent chance of winning.
• Chancellor's play keeps the Seahawks up by three, giving them an 89.5 percent chance of winning.
• Had the Seahawks been penalized for illegal batting, Detroit would have had a first-and-goal inside the 1 with 1:45 to play, giving them an 80.7 percent chance of winning.
The percentages for the first and last scenarios might not seem very high for Detroit, but that's because Seattle had two timeouts, leaving plenty of time for the Seahawks to respond (also assuming Detroit scores quickly in the last scenario). Ninety or more seconds is a virtual eternity in the modern two-minute drill.
Overall: The officials' missed call on the batted ball was a plus-.702 win probability added event, as we might say in the football analytics world. In other words, it swung each team's chances by about 70 percent. It's very rare that single events in football even approach that big of a swing.
The difference between the 80.7 percent chance following the hypothetical illegal batting penalty and the Lions' 10.5 percent chance following the touchback makes that missed call a 70.2 percent error.
That might not be as big as the "Fail Mary" call in the Green Bay-Seattle Monday night game three years ago, which was a clear-cut 100 percent swing, but it's close.