Lots of water coming out of chicken breasts when cooking in pan. Why?
Liquid naturally comes out of all meats as they cook. If you're using high heat and a frying pan, you don't really notice it because it evaporates quickly. That brown stuff you see in a frying pan after cooking meat on high heat are the evaporated juices. 

If you're baking them at around 350 F, you'll also notice water being released. This is amplified if you overcrowd the cooking vessel. You don't see it in a whole roasted chicken or roast beef for example because the liquid coming out caramelizes and creates those lovely browned bits to make a sauce or gravy. 

I doubt that WF is selling water and phosphate tumbled chicken breasts.