The elbow never moves to create the slant, so we can go ahead and cancel the idea of using the elbow to help slant and straighten the bar. The slant is done with the fingers (see the topic on how to practice slants).  So the arm position that is working the bar stays as close to the same angle as you move the bar up and down the neck.  The wrist may help to move the fingers that move the bar into the slants, but the main motion that moves the bar into the slant comes from the fingers and thumb. So, when you do the forward slant by pushing the tail end of the bar back with the thumb and the nose end forward with the second finger behind the bar, to straighten, you will push the tail end back straight with the bottom end of the second finger as the thumb moves back in position.