Blueberry plant disease
It's never a good day when a beloved plant is showing unhappy symptoms. This looks like it could be a number of things, including fruit russeting from overhead watering, cankers, or bacterial blight.
To help narrow it down, I have a few questions: what does your irrigation look like? Are your other blueberries affected? Have you cut open any berries to look for larvae?
If it is in fact bacterial blight, a common blueberry disease, I've included more information below:
"This disease is caused by the bacterium Pseudomonas syringae pv. syringae and is a problem in production areas west of the Cascade Mountains. Bacterial canker can be particularly severe on young plants in new plantings because a high proportion of the wood is succulent and susceptible to disease. Wounded tissues provide entry sites for the pathogen into the plant. Disease severity in the spring is often greater following frost injury the previous fall. Only canes produced the previous season are attacked. It is important to prune out all diseased wood as soon as it is noticed, especially before fall rains. Prune susceptible cultivars during dry weather if possible. Avoid late-summer nitrogen fertilizer applications that can lead to winter injury. Several products can be used for chemical management, but all have copper as an active ingredient. Multiple applications, low rates or both encourage resistance to these products. Spray twice, first before fall rains around the first week in October and again four weeks later." - Jay Pscheidt