How are they not going to make an impact? Impacts can be positive and negative.
Now you are going to have potentially key players missing from Orlando, Philly, Boston, and others. You do not know where some free agents are going to be. Using 2012-2013 numbers is going to be tough when missing Bynum, Love, and Rose and not to mention the unknown of Kobe and Rondo. Using the sim is useless. Swagging it would be more likely.