This has happened with native transplants for me.
Say, for instance, I dig up a large Dryopteris - maybe two foot fronds - and plant it in my yard. The following year, the fronds *will not* be two feet long. The fern has to grow roots, adjust, et cetera. On average, ferns take about three years to really establish themselves.

This has been true of my Woodwardia, Dryopteris, Polystitchum, and Pentagram ferns.

As long as the ferns can survive your climate, they should gradually re-assert themselves!

Josh

Josh, Thanks for your input. I know most of the ferns I have take a couple of years or more to really take off, it's just that these really regressed! -I'll just be patient and overlook the big empty spots where I thought I would have ferns this year! -Thanks again! GC