It would have to be really large hail to do that and you would see signs of damage on other plants and tree leaves in the same area. Another theory: Deer love hydrangea. My friend lives in an area where there are quite a few deer and she must spray hers with a bad tasting spray to save them from being eaten. Last year she forgot to spray and came home to find the deer had come through her yard and eaten all the new buds off the plants. She was not happy!!!!!!!!!!!!

Pea-sized hail can do a number on soft leaves as on a hydrangeas. ( anad Have on mine.)

But rather than looking eaten -- that is, missing pieces -- you'll see linear tears.

Here is a link to foliage damaged by hail...

Here is a link that might be useful: