Besides an army of hungry slugs, what could be eating my daylilies?

Cultivars: Caribbean Frank League, Footprints

Problem: Notwithstanding robust growth, strong scapes, good sun exposure, good bud count ...

... the scapes are stunted and the quality of the flower is poor.

Could it have been our very long. cool, wet spring here in Northern WA?

Our heavy clay soil?

Something else???