Mike Lowell is a class A free agent.
The Yankees lost 4 class A's (Pettitte, Posada, Mo, Arod) and a class B (Viz).
This year, they can only sign as many as they lose.
To sign Lowell would be a fourth 'A' free agent.
Either the Yankees are sending a message to Pettitte to hurry up his decision, or they're sending a message to the league that they're moving on without him.