As a plant pathologist, I choose your second guess. If you have a lot of rain, your tree is in one place, it does not get good air circulation, it is susceptible to Botrytis flower blight. Botrytis cinerea is a ubiquitous, so the only way to avoid it is for C Welding environmental conditions (you can use fungicides, but they do not provide good coverage of the rapid opening up parts like buds and flowers.