Freezing roasts?

I was having some friends over for dinner tonight and thought I’d be all Christmassy, since I never do the real Christmas lunch myself because I always have to travel to family, and have roast turkey. Unfortunately it has now been postponed due to illness, so I now have this lump of turkey that has already been frozen (and defrosted). Does anyone know what happens if you roast meat, then freeze it (whole) then thaw it again? I’m guessing the result would be something rather terrible ...