Bill is correct, but I would modify what he stated above just a bit. You need to move your eye in the direction you want to move the POI. Moving the comb is the typical way to move your eye. Sometimes, moving the pad can result in moving your eye.
LOP is measured from the trigger to the middle of the pad, most generally, although, I have seen it measured to "heel and toe". Any movement of the "midpoint" of the pad changes the LOP, to some small degree. It is therefore likely you would not notice any change.
If you removed your pad and tempoarily reattached it with some 2-way tape or sticky foam, you can determine if there would be a noticeable difference to you.-Jerald
He did Frank. I.Hartman, moving the pad down, within reason, will make you shoot with your head more erect. When you stop seeing the same bead alignment, your POI will shift, not before.
Try it and see what happens. Lowering my pad made a world of difference. So did moving it right. My old stock had "classic" dimensions. You know, the dimensions the experts say is "right" for everyone. Well, lowering the pad raised my head so I was no longer looking out the very tops of my shooting classes. Moving it right effectively moved the comb closer to my face so I didn't have to lean my head to the right to see straight down the rib. Now my eyes are level and I am looking through the optical centers of my lenses. It's great. I am much more comfortable, and much more consistent. So much for the "experts".
The second sentence talks about the comb and I was trying to add to what Shawn had stated. I should have been clearer about my answer as Pat indicated.
IMHO, generally, if you have a parallel stock, moving the recoil pad should have no effect on the relationship between your eye and the end of the barrel (or beads - which ever you prefer). Lowering the recoil pad does have all the advantages that zzt mentioned. If you have a classic style stock (not parallel) then it changes everything, you may in fact lower the POI, because your face is further back on the stock. Bill Malcolm