Protection is about depth. Not about choosing between pitching to one or two guys. I believe Sharp when he says having Dunn right behind (or occasionally in front) of Zimm has little to no statistical impact, but when you've got 7 or more guys in a lineup that can beat you, that's where your protection becomes more real. That's why the Yankees and Phillies have some of the best offenses in baseball, it's because there's no holes in the lineup.