In Michigan, we would suspect an insect such as cranberry fruit worm. This small moth lays eggs on the fruit at petal fall. The larvae tunnel into the fruit and feed, causing the green fruit to color prematurely and usually drop before harvest. You can see the frass from the larvae and sometime webbing holding adjacent berries together. Fruit infected by the mummyberry fungus also turn an off-color. If you cut these fruit open, you will see white fungal growth within the berries. You might check with your local extension experts to see if these are problems in your area.