The problem is, that Parisi could come as a back-up player, who could sit on the bench. Just if he really plays great, and he turns out to be a great buy, he will be a starter, and Zambrotta will play in midfield.
Evra would only come as a starter, as he is known, would be very expensive and he I would never like to see Evra on the bench.
Parisi is cheaper and would come as a sub-player.