NNG: Turning Steam Locomotives on wyes

Not a narrow gauge question per se, but I watched a show tonight about the Ohio Central and one of their rebuilt steam locomotives. It was mentioned during the story that the Ohio Central does not like to turn the locomotive on the wyes it currently uses. I have heard this same comment a number of different times from various steam programs. I understand that some of the wyes may have been re-laid or built with curvature too tight for the big steam locos, but many of the wyes now being used are the same ones used back when theses steam locomotives were new. I was told by a MOW manager that a number of years ago the UP had some type of mechanical issue with the #844 and wanted to turn it in at either Lagrande or Telecaset Oregon, but couldn't / wouldn't. As far as I know, these are the same wyes that handled 2-8-8-0's in the heyday of steam. Isn't a 4-8-4 easier to get through tight trackage than a 2-8-8-0? Granted, some of the wyes I have seen don't look like they've had much maintenance in the last few decades, but still...Other than size limitations, what are some of the other reasons why these locomotives wouldn't be turned on certain wyes?