Seems to me the more you can set it up pre-snap so that
there ends up being a race to the ball... more like a mad scramble than a rock-em-sock-em-robots thing as it's always been... and with the receiving team having some advantage but not an extraordinary one,
then you can accomplish the desired 13-14%
while also retaining a legitimate effective constraint embedded in the rules to ****** full-steam head-on collisions.
(Problem is, you have to have a testing ground to determine the exact parameters... ie, what yard lines are most ideal... that get you at the number you're seeking, so until you have that, it's all just a theoretical conversation.)
And for example, you could say...
- Kickoff from 35 (as current).
- Receiving team may only have players lined-up between the 40-45 (kicking team's side of field) and beyond their own 25 (... current, they can be no closer than the 45). Thus, the 25-50 on their side of the field is no man's land, pre-snap. So, in the screenshot below, imagine all the LAC players shifted about 5 yards up
- Kicked ball becomes live once it passes the 50 yard line (instead of kicking team's 45).
Would look something like this...