Well firstly, I just realized that the expression does not account for files which already contain (MVC) in the name, so it's not what you would want anyway.
Personally, I would customize the view you're using with this expression, rather than renaming the files.
If(IsEqual([File Type], mk3d, 1), If(!IsEqual(Right([Name], 5), /(MVC/), 1), Delimit([Name],/ /(MVC/), ), [Name]), [Name])