You were spot on with the MO=Deparse recommendation. Since you all took the time to help me out, I'd like to mention that I resolved this issue (finally!) and figured out the issue.

As it turns out, in my Program::Plist::Pl package, I use Program::Types qw(Pattern) This results in importing a subroutine into my package with the same fully qualified name as my Program::Plist::Pl::Pattern package. The result is that when I was saying Program::Plist::Pl::Pattern->new I thought I was saying 'Program::Plist::Pl::Pattern'->new(). However, I was really saying &Program::Plist::Pl::Pattern()->new(). And that's how I was ending up off in MooseX::Types land instead of inside my constructor.