Is onside kick the equivalent of lottery for NFL teams?

You are inside the 2-minutes warning, you just scored and closed the gap to an one-posession game.  You align the team for an onside kick  hoping to get the ball back and score again.  But the key point is the word “hope”.  The odds are so much against you at that point that it might not be far-fetched to say that it is like playing a lottery (far from 50-50).

I analyzed the onside kick attempts for the last 7 NFL seasons.  What are the success rates? As you can see, between 10% and 20% is what you should expect overall.  So the odds are pretty low to get the ball back – let alone to win the game.onside_yearly

Of course not all teams have the same skill at the kicking position (even though it appears that overall onside kick is not a matter of skill) and hence, there might be differences for the rates between the different teams.  The following figure has the success rate per team for the seasons 2009-2015.

onside.jpg

Patriots, Chargers and 49ers reach the 40% mark (43%, 42% and 40% respectively). However, the sample set is extremely small (number of attempts is provided at the top of each bar) to make any strong claims about the teams’ performance on onside kicks. For example, the confidence interval for the Patriots’ onside kick success rate is [0.072, 0.808], i.e., the true success rate can be anywhere in this (not small) interval!

But what if teams tried earlier in the game for the onside kick? It can be the case that the hurry-up and stress mode, together with the tiredness of the team, leads to the extremely low success rates.  Gladily we can test for this since there are instances of onside kicks during the first 3 quarters of a game, a timing when these factors (stress and tiredness) might not be present.

onside-quarter

As we can see the success rate when teams try onside kick during the first quarter is much higher (almost 48%).  In fact, even the lower end of the 95% confidence interval, i.e., 25.5% is much higher than the higher end of the corresponding confidence interval for the fourth quarter (15.5%).  In fact the 95% confidence interval for the onside kick success rate during the first 3 quarters is [28.5%, 51.5%].  Compare that to the [8.5%, 15.5%] for the fourth quarter.

Maybe it then makes sense to try get the ball back earlier in the game through onside kick, so as not to have to rely on it at the end of the game.  In the latter case, you might as well play the lottery.

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