Love the concept:
1. adds excitement, great QB vs defense late in game
2. game decided by offense and defense rather than a kickers ability to high bounce a ball
3. even if successful, you’ve got gain yards to scores afterwards.
4. current onside kick recovery rate is 8%
the downside:
1. limitations? Name another sport you can only do x when losing? And only twice in a game? A hockey team can pull goalie whenever they like? You can steal a base or intentionally walk a batter whenever.
2. any math supporting 4-15 is likely to be better than 8% conversion rate?
3. Penalties. It’s a 4th down play, an offensive holding gets a first down? Would official put away the flags on this play? what happens if offense gets a holding call? 4-25?
this is x=y, might be too many moving parts
modify the onside kick might be simpler because the way it currently works isn’t good enough.