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.