I see two problems here. In the first image, the primary problem looks like cracking is the main problem. This occurs from uneven watering or excessive moisture after a dry period. It is also more of a problem in certain cultivars. I am not sure if this variety is prone to that or not.
The other problem, which may also be contributing to the cracking, is bacterial spot or bacterial speck, seen pretty clearly on the second picture. You should also see dark spots on the leaves of the plants too, surrounded by a yellow halo. These are common diseases during wet weather. Unfortunately it is quite difficult to control because it is caused by a bacteria instead of a fungus - fungicides will not work and at this stage of the game it is likely too late to do much anyway.
Culturally there are several things you can do in the future. Space plants well apart, stake or cage to allow good air circulation, use mulch to cover soil after plants are established, use drip irrigation or soaker hoses instead of overhead sprinkler irrigation and remove all plant debris at the end of the season.