So theoretically, the Yankees can offer Josh Hamilton (just an example) a one year deal worth 35M with 3 club options worth 15M each. In essence, that's a 4 year contract worth 80M. The AAV will be different though because they are club options. If its a normal 4 year / 80M dollar contract the AAV would be 20M per season which would hurt the payroll. This way (1 year deal plus option contract) the AAV for the first year would be 35M but only 15M per season for every other year the player is under contract due to the years not being 'guaranteed'.
The MLBPA can't even really ***** about this contract. The Yankees won't actually be avoiding the tax. They will be 'accelerating' payment for the player.