Published: 04 January 2015
Immediately following the huge reversed penalty
, the Detroit Lions were faced with a 4th-and-1 on the Dallas 46, up 20-17 with 8:25 left in the game. The Lions decided to take the delay of game penalty, and then punt - which ended up as just a 10-yard punt. Obviously, the Lions did not anticipate such a bad punt, and we cannot judge the decision based on the outcome, but was punting the ball up three the best decision?
Before the delay-of-game, after the incompletion, the Lions had a 66.6% chance to win the game. After the penalty, that dropped to 60.6% (-6.0%). With a conversion on 4th-and-1, the Lions' win probability would have jumped to 76.6%. If the Lions failed, that would drop to 53.9%. With a punt, the expected win probability would be 66.1%. The expected conversion rate on 4th-and-1 in that section of the field is 65.3%.
My numbers here are very similar to Brian's from the 4th Down Calculator:
With my numbers, the E[WPGo-For-It
] = 68.7% > 66.1% = E[WPPunt
]. That makes the break-even point 53.7% (nearly identical to Brian's 52%). Remember, this is just league baselines, so other situational factors and team strength do play a role in the decision. But, based on averages, it appears the Lions sacrificed about 1.6% win probability by deciding not to go for it on fourth down. This is not an enormous loss, so we cannot fault Jim Caldwell too much. He talks about his decision here
Unfortunately for the Lions, Sam Martin shanked the ensuing punt and the Cowboys would go on to score the game-winning touchdown.