It looks like your phlox is suffering from iron chlorosis. Basically, it is a nutrient deficiency. 

Your phlox is planted in rocks and my guess is there is a layer of plastic under those rocks making it difficult for the plants to receive much water or nutrients. They are also experiencing the heat from the rocks. 

You could try spraying them with a foliar plant food for a temporary fix but over the long run, they will not do well in this environment. 

https://extension.umn.edu/flowers/tall-garden-phlox

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/environmental/iron-chlorosis

While it is true that we are getting lots of rain this year, that rain is not getting to your plants because it can’t seep through the plastic that is under the stones. They probably have a very small opening around them where they were planted. 

You could try feeding them with a very weak fertilizer to help them in the short term but I don’t believe it will work over the long run. It’s worth a try.