Currently the only incentives allowed in contracts are for winning awards or making the All-Star team, or for "games played" or games started for pitchers, etc.
It's currently illegal to have incentives for specific statistical achievements and I hope to god it stays that way. You start having incentive clauses for homers, stolen bases, etc. and you'll warp the game. Guys will be stealing in the 7th inning with their own team down by 8 runs, etc.
Are you saying that the owners could pay salaries such as ARod's if the price tickets weren't so high? It's a cycle that has to be broken.