A model-based approach to football strategy.

September 19, 2006

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2006 Week 2 Strategy Review: New England at Jets

Brief strategy reviews will appear occasionally during the 2006 season, limited to situations that differ from those analyzed in previous years.

With 1:15 left in the game between New England and the Jets, the Patriots led 24-17 and faced fourth-and-one-foot at the Jets' 7-yard line. The Jets had no timeouts. In an attempt to draw the Jets offsides, the Patriots lined up as if they were going for the first down. The Jets couldn't have been fooled: a field goal ends the game as effectively as a first down, and has a much higher chance of success. As the play clock predictably ran down, the Patriots took a five-yard penalty for delay of game rather than call timeout. (The ensuing field-goal attempt was blocked, but New England held on for the win.)

When asked about the delay-of-game penalty during his post-game press conference, New England coach Bill Belichick said that he "didn't feel like five yards would make much of a difference." That's true in the sense that the Patriots remain highly likely to win even after the penalty. But as we will see, Belichick's tactic roughly doubled the Jets' slim chances of winning.

In order for the Jets to get back into the game, the Patriots have to miss the field goal attempt, and then the Jets have to score a touchdown. The delay-of-game penalty actually makes the field goal much less certain. Twenty-five-yard field goal attempts fail only about 4% of the time, whereas 30-yard attempts fail about 10% of the time. Even under the optimistic (for the Patriots) assumption that the Jets have a 20% chance of jumping offsides, Belichick's tactic gives the Jets a (1 − 0.2) × 0.1 = 0.08 probability of getting the ball back with a chance to tie. If the Patriots simply attempt the field goal from the 7-yard line, the Jets have only a 0.04 chance of getting the ball back with a chance to tie. If the Patriots insist on trying to draw the Jets offsides, they should use their final timeout before the play clock expires, rather than take a penalty.

[Note: This calculation slightly understates the cost of the penalty. If the field goal attempt fails because it is blocked, then New England's delay-of-game penalty generally leaves the Jets with five fewer yards to go on their subsequent possession. According to the model for the two-minute drill, this effect is not negligible in percentage terms. We estimate that the Jets have a 0.066 probability of scoring a touchdown starting from their 15-yard line, compared to 0.081 starting from their 20-yard line.]

Copyright © 2006 by William S. Krasker