Sunday, November 17, 2013

Underdogs Shouldn't Play for Overtime


In week 9 of the NFL season, the Buccaneers nearly pulled off an historic upset playing on the road against the heavily favored Seahawks. The Bucs were a 15.5 point underdog, yet somehow found themselves leading 21-0 with just over two minutes to go in the first half. Going back to 1989, only three NFL teams have won a game as a 15.5 point or greater underdog.

When playing as an underdog, there are a couple things a team can do to maximize its chances of winning:
  1. Go for high variance plays (surprise onside kicks, going for it on 4th and short, two point conversions, deep passes, etc.)
  2. Shorten the game when possible (when you're the underdog, the house will eventually win if you stick around long enough, so cash out while you can)
Credit Coach Schiano for calling for a surprise onside kick in the second quarter. The Seahawks recovered the kick (just barely), but it was still a smart call. Late in the game, Schiano had another opportunity to make the right call....

Losing as slowly as possible

As the game wore on, the Seahawks mounted their inevitable comeback, tying the score, and Tampa Bay found themselves facing a 4th and 3 from the 50 with about 40 seconds to go. Instead of attempting a conversion and going for the win in regulation, Coach Schiano chose to lengthen the game, punting to the Seahawks and playing for overtime, which Tampa Bay promptly lost.

According to the Advanced NFL Stats 4th down calculator, punting was the wrong decision: Going for it had a win probability of 0.55, while punting had a win probability of 0.47. But even that understates how bad of a decision that was. The ANS calculator presumably values overtime as a 50/50 proposition for either team. And while that has to be true on average, it is definitely not true for underdogs. Underdogs only win 44% of the time in overtime in the NFL. And underdogs of 10 points or more have only won 38% of the time.

Schiano probably thought he was taking an even money bet in overtime, when in fact he was facing something closer to 3-2 odds. And while being a heavy underdog also shortens their odds of driving for a game winning field goal in regulation, that impact should be smaller than the overtime impact as it involves fewer plays in which team disparities can accumulate. While not directly applicable to this situation, heavy favorites and heavy underdogs do not show a very marked difference in their ability to convert 4th and 1 situations (league average conversion rate is 68%, while a 15 point underdog would be expected to convert 64% of the time).

Underdogs and Overtime - The Evidence

To illustrate this point, I have compiled overtime results for four different sports: NFL, NBA, NCAA Men's Basketball, and NCAA Football. The results are remarkably consistent: Underdogs fare poorly in overtime, and heavy underdogs fare even worse.


NFLNCAAFNBANCAAB
Underdoggameswongameswongameswongameswon
1 to 5 points20046%12248%42348%85444%
5 to 10 points12942%10442%28933%52335%
10+ points2038%9235%3832%20327%
Total35044%31842%75041%158039%

The strategic implications go beyond football. In basketball, a heavy underdog may be better served by going for the walk off three pointer as opposed to the higher percentage two point play to send things to overtime.

There is also a broader point to be made regarding in-game results and small sample sizes. Just because an underdog fights its way to a draw after four quarters doesn't mean it has proven itself to be equals with the favorite. What the table above shows is that, for the most part, underdogs are who we thought they were. Similarly, just because your kicker missed his first three kicks of the game doesn't mean he's guaranteed to shank all future ones that day. One early fumble does not mean your running back will be a turnover machine. And just because you got stuffed on your last couple short yardage plays doesn't mean you should punt on 4th and 1 from your opponent's 38.

Data for this study courtesy of sportsdatbase.com.

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