Perplexing Puzzler

ProfessorRoush is not sure what was unique about last winter, but there was a disturbing desertion from the garden this spring, a vexing vacancy of one of my most annually-anticipated arrivals.  Sadly, my 'Mohawk' viburnum did not bloom, nay, it did not even bother to leaf out.  Normally, this corner is one of my favorite early spots in the garden, but not this year.

All the other viburnums in my garden, 'Juddii' (see pictured on the lower left), 'Opulus', 'V. burkwoodii, V. carlesii, 'Roseum',  all these leafed out on schedule, fragrant and full.  But not 'Mohawk'.  Even now, after 'Juddii' has faded and dropped its blooms, settling in for a season of quiet growth, 'Mohawk' remains leafless, a mere twiggy skeleton, conspicuous in its absence.

Viburnum 'Juddii'

But I'm just scratching the surface of this mystery.  Literally, as I scratch the surface gray bark of 'Mohawk',  the inner bark is still green, all the way to its tips.  Will it yet undergo reincarnation?  Can I hope to see it leaf out and live on into next year?  What caused this lack of spring season rebirth?  Was it the extreme drought of last summer?  The subsequent wet fall and winter, drowning in the roots grown deep to keep it alive? Did a late freeze catch it just at its most vulnerable time, leaf and flower buds on the cusp of expansion, only to be frozen in time?

I'm actually leaning toward the latter theory based on the supporting evidence that almost all of my Rose Of Sharon (Hibiscus syriacus) are also either very slow to leaf this year or partially dead or both.  Several of those have yet to do anything, while a few are leafing out slowly and carefully, as if they were expecting cold weather yet.  These too, are still green beneath their outer bark.  To have a whole genus caught out and damaged by weather doesn't surprise me as much as a single cultivar of a genus, early bloomer though 'Mohawk' may be in relation to its relatives.

Any theories or advice out there among yee gardening Sherlock's of the internet?   Grub out 'Mohawk' and replace it (since I love it too much to do permanently without), facing the inevitable, or hope for self-rejuvenation and a gentle summer?