What an artificial distinction to make! Perl 5 exists as it is for the sake of backwards compatibility. Very few misfeatures suffer deprecation, few deprecations experience removal, and almost any code example you can find as far back as 1987 runs unmodified on Perl 5.13.x (whichever monthly release is the most recent).

I also find it difficult to compare language features between Python and Ruby or Perl when neither Python nor Ruby can get lexical scoping right. That seems like a very basic principle of language design.

Update: I forgot to write that Perl 6 is the Perl version which explores improvements in the core language.