The end of the summer was pretty busy for me, so I haven't had time to do any posts on here. But I'm back now, although with a short post about something that's not hockey related. Hopefully you'll still find it interesting.
While watching college football with friends last weekend, I was reminded of how frustrated I get when teams bring kickoffs out of the endzone but don't have at least a 25 yard return. For anybody unfamiliar with college football rules, any player who catches a kickoff in the endzone can kneel down, and his team will start their drive on the 25 yard line (20 in the NFL). The player also has the option to run the ball out of the endzone, and his team starts their next drive where he is tackled.
The main question here is, should a kick returner ever bring the ball out of the endzone, if he catches it there? If the average length of kickoff returns that start in the endzone is at least 25 yards, then it probably makes sense to run the ball out. If the average length is less than 25 yards, then he probably should kneel down and take the 25 free yards. From some basic analysis, I find some pretty compelling results that suggest that the latter strategy should be the dominant one. Specifically, I show that about two-thirds of all kickoff returns that start in the endzone do not make it to the 25.
To answer the question, I collected data for every kickoff that occurred during the 2012 college football season (games featuring at least one Division I team). This resulted in data from over 9100 kickoffs in over 850 games (there were a few data and HTML errors on ESPN's website, which meant I had a couple missing games/kickoffs).
During last season, there were 5053 kickoffs that landed in (or beyond) the endzone. Of these 3673 were touchbacks, either because the kickoff returner caught the ball and knelt down or because the ball landed behind the endzone. That leaves 1380 kickoffs in which a player caught the ball in the endzone and opted to return it.
Of these 1380 kickoffs, the shortest return that occurred was one yard, which happened twice. This likely resulted from a mishandled catch. The longest returns were the 15 that resulted in a touchdown after a return of more than 100 yards.
More important to the question at hand is the average kickoff return length for balls caught in the endzone. For these 1380 kickoffs, the mean ending point of the runs is the 23.77 yard line, and the median end point is the 21 yard line. These two pieces of evidence suggest that players that choose to return kicks out of the endzone are, more often than not, giving up field position that they would have received had they taken the touchback in the endzone.
The graph above shows the distribution of how far these 1380 kickoffs went. The x-axis corresponds with the yard lines on a football field, and the y-axis indicates how many of the 1380 kickoffs ended at each yard line. The red horizontal line is placed just below the 25 yard line. Any runner that is tackled to the left of the red line probably should have never run the ball out of the endzone.
Before I collected the data and crunched the numbers, I expected the find that (more often than not) kickoff returns starting in the endzone don't reach the 25 yard line. I was pretty shocked to find that the proportion of time the runner doesn't make it to the 25 yard line is 67%. Two out of three kickoff returns that start in the endzone result in the ball carrier conceding yards which he could have freely received had he not left the endzone.
A few closing observations. Touchbacks don't shift momentum in a game. If a team is trailing in the fourth quarter, it might make sense to ignore the data and try to break a big run (maybe even return one for a touchdown). The odds are still against them, but desperate teams have to resort to desperate measures.
Another thing that I wasn't able to find data about is how deep in the endzone the kick landed. The endzone is 10 yards deep, so it seems reasonable to think that a kickoff caught one yard deep in the endzone is more likely to be returned to the 25 than a kickoff caught 9 yards deep in the endzone.Without those data, I can't say whether my conclusions are valid for returns starting anywhere in the endzone, or whether my results are driven by the fact that it's harder to get to the 25 if you started 9 yards deep in the endzone. I don't think this is a huge concern though because kick returners rarely return kicks that are caught more than 5 yards deep in the endzone. As a result, my results are most likely driven by kicks that land only a few yards into the endzone.
So what's the takeaway? I'd advise any college coach to train his players to almost never return kicks that they catch in the endzone. "Never" sounds like a stretch, since 33% of the time returning a kick actually pays off, but there will always be players who ignore their coach's advice and bring kickoffs out.