SCurtis said: ...The two I took out the root balls were very small actually, I was very surprised that they hadn't gone too far out of the planting pot size that they were originally.
Ah...okay. That explains a lot. Evidently your watering regime was a little too prompt. Next planting time try watering them just once a week instead, but for a longer duration. Those roots need to have a chance to go down to find moisture, otherwise they don't grow enough to supply nutrients for a big, fully-fruited plant.
For the crop you have now; I'd mulch them well, reduce water somewhat to control nutrient leaching, and apply a good lower nitrogen foliar food. Too much N will cause the problem to worsen, I think; adding top growth that can't be supported by the plant roots.
I still remember a time, way back, when a very young, old-timey veggie gardener told me, "Nah, we don't water 'em; just a dipper at planting time to take out some air pockets, and that's it." It's good advice because it demands that the plant grow a big, strong root mass before the top growth takes off.
