NFL Advanced Analysis: Breaking Down the Potential Kickoff Changesby Keith Goldner on Dec 7th, 2012 · 0 comments
This post was originally written by numberFire Chief Analyst Keith Goldner for his personal site, Drive-By Football. Check it out!
Recently, ProFootballTalk published an article discussing potential plans to eliminate an opening kickoff entirely (H/T to Abe Schwadron of TDDaily.com).
"Sean Gregory of TIME writes that one of the options being considered for replacing kickoffs entails giving the ball to the team that would have been kicking off at its own 30, automatically facing a fourth down and 15 yards to go. The team can then choose to punt or go for it, via fake punt or otherwise. In other words, the kickoff would be replaced with the punt, and the onside kick would be replaced with a fourth-down conversion roughly half the distance of Ray Rice’s recent catch-and-run."
Obviously this concept piqued my curiosity, so I decided to run the numbers. A couple of things to note:
- Surprise onside kicks would be replaced by fake punts. It is the same concept, the return team expects a deep kick based on formation, but the kicking team fakes.
- Regular onside kicks would be replaced by 4th-and-15 attempts.
- Punts can be blocked or botched with bad snaps -- regular kickoffs obviously cannot.
- It would be very hard to force a touchback from a punt from the 30.
- You could kick the ball out-of-bounds to prevent a return and the opposing team would not receive the ball at the 40-yard line automatically.
- Teams can gain far more yards on a 4th-and-15 attempt than they could on an onside kick attempt
- This would be done for safety purposes and I question whether kickoffs are significantly more dangerous than punts (although I assume they are, otherwise this never would have been suggested).
- There will be way more penalties on punts than there typically are on kickoffs -- including false starts.
I tried to incorporate as much as possible into the analysis, here are the probability and frequency breakdowns.
Based on the adjusted expected points value at the bottom, the punt would result in twice as many expected points as the current kickoff rule (1.15 versus 0.53) for the receiving team. The majority of that comes from the difference in average starting field position. Kickoffs from the 35 have resulted in an average starting field position at the 21.6, whereas punts from around the 30 result in a starting field position of the 30.4 yard line. This also assumes that teams will fake punt/go for it on the 4th-and-15 as frequently as teams kickoff onside or surprise kickoff onside.
The biggest difference other than those mentioned above (all the poor outcomes possible for punts) is the change in the probability of converting a surprise event. Surprise onside kicks convert at an extremely high 60% rate -- and should most likely be attempted way more frequently than they currently are. Fake punts from around 15-yards convert at roughly the same rate as a regular 4th-down attempt -- keep in mind this is just an estimate since this scenario occurs extremely infrequently. The defense has a much better chance to stop a fake punt that has to convert 15 yards (either a 15-yard run or completion) than they do to recover a bouncing ball that the only requirement is for it to travel 10 yards.
The next step would be to look at injuries and the severity of injuries on kickoffs and punts. I'm sure the NFL has researched this and found that the average number and especially severity of injuries is lower on a punt than a kickoff, otherwise this never would have even been mentioned.
One other note is that I would guess teams would begin returning punts more frequently than they currently do (less fair catches) -- just like we saw teams start returning balls from deeper and deeper in the end zone when the kickoff was moved up.