> Solution: light-up accelerometer helmets, and a new rule that if the helmet lights up it's a penalty

I like this idea.

Many motorsports (such as Formula 1) have safety accelerometers that require medical checkup to the driver when tripped (I think around 25-50 G impacts). It also alerts the track officials to take special care if the driver has to be extricated from the vehicle. There have been incidents in the past when a driver has walked away from the crash, but later developed a headache and died in the following days.

How do you disincentivize both teams in a zero-sum game?

It's not a zero sum game, the football leagues are businesses engaged in maximizing revenue while minimizing liabilities. Injured players are a liability.

In American football at all levels there are already severe disincentives for dangerous hits such as helmet-to-helmet collisions; these usually start at a 15 yard penalty and escalate to ejections and suspensions.

You can't give both teams a 15 yard penalty. How do you set up a rule so you don't incentivize teams to 'draw the foul'?

One question to ask is, given the history of the existing 'unnecessary roughness' / 'illegal hit' rules (which have been around for decades), why haven't teams been incentivized to 'draw the foul' already? (in the nfl, faking an injury at critical times is already disincentivized, see http://static.nfl.com/static/content/public/image/rulebook/p... section 5 article 4 page 18)

Also given how much time is spent going over videos of games after the fact (at all levels from high school on up), someone trying to draw the foul stands a pretty good chance at being caught out at it, which opens them up to, say, getting a multi-game suspension.

Money seems like the simplest solution.

I think that's a great idea - I wouldn't try to link it to rule changes, but having players instrumented so you know that there might be a problem so they can stop playing and maybe get a checkup is a great idea.

Build something like into a rugby scrum cap and I'd buy one for my teenage son in an instant.