Yes, Luis Castillo is a cow.
I'm under the impression Johan only has the change, fastball, and slider. The only way I'll change that is if you're a Twins fan by trade and see him pitch all year round. He throw a hard slider, maybe that's why it looks like a cutter.
If you can think of better fits for those 3 batting stances, be my guest. Morneau is the only one I personally have a problem with, but there's none in my opinion that suit him better.
And Silva is tough to rate because he has such immaculate control. I'll ask SwinginSoriano about whether or not he'll decrease the "goodness" of him. I agree with you that he's not THAT good, but the game takes control into huge consideration regarding how good a player is.