If Johnson is traded, then Phil Hughes or Humberto Sanchez will be promoted to the rotation, which would then look like this:
1. Wang
2. Pettitte
3. Mussina
4. Pavano
5. Hughes
That's pretty good.... Wang could easily win 20 games, while Mussina and Pettitte will pick up at least 15 victories. Pavano, if he's healthy, may be baseball's best #4 starter, and if Hughes is all he's supposed to be, the Yanks might be undefeatable.
But I'm still surprised the Yanks are looking to trade Johnson. I know he's bad, but he's a good veteran to have at the back of the rotation. Keeping Johnson for one more year would give him a chance to win 300 games with New York and Hughes another year of experience in the minors.