No museum exhibition is perfect, but some are less perfect than others. Surprisingly, even these shows sometimes turn out to be exceptionally valuable. They clarify notions of quality and the pleasures and rigors of looking, for curators and visitors alike.

“Embracing Modernism: Ten Years of Drawings Acquisitions” at the Morgan Library & Museum is one of these flawed gems. Of its nearly 100 drawings, about half are either weak or just acceptable, which is not good enough for an institution of the Morgan’s stature.