Since 2003, revenue grew 247% and player payroll increased by 149%. Players say the cap isn't a cap on revenue but only on player salaries.

A lot of new money has come into baseball, including from private equity firms. For owners hoping to sell, a cap could boost team value.

The MLB Players Association made its initial pitch on a labor deal; the owners will make their first proposal Thursday.

This is the first salary cap put forward since 1994, which led to strike action