So the idea of protection is based on the idea of a distraction?
Not trying to run off on that tangent. But why would the guy on deck be any bigger of a distraction than all the other potential distractions happening at any moment in a baseball game?
Protection is one those things that makes sense in theory but there is no evidence of data to support it's existence.
Let's look at Miguel Cabrera the last two years
In 2011 with Victor Martinez batting behind Cabrera 140 times on the season, Cabrera saw
59.6% fastballs, 15.6% sliders, 6.9% cutters, 7.1% curveballs, 9.2% changeups
In 2012, with Prince Fielder behind.
Cabrera saw 59.2% fastballs, 15.4% sliders, 6.2% cutters, 9.6% curveballs, 7.7% changeups.
So the only variation really was more curveballs and less changeups, and that's only to the tune of 2%, which most likely has nothing to do with Fielder.
This is only one example, but every example fits. You don't get pitched differently based on who is on deck.
Here is a decent and recent fangraphs submission on the topic that was quite good analyzing Fielder and Cabrera.
http://www.fangraphs.com/blogs/index...ion-look-like/