How well did Cotto's jab work on Pacquiao?

I don't think Pac has ever actually slipped a jab on the inside; he prefers to slip an orthodox jab to the outside. Wouldn't it make more sense to feint the jab and throw a low left hook (since usually, the right hand won't be in any position to throw back) because Pac may or may not **** his hand back for a right hook.