Why are you using substitutions in a "count" script?
And then replacing whatever it was with itself?

Best to not modify your input and risk changing things while you're trying to count.
Note: See Perl Idioms Explained - my $count = () = /.../g

use strict;
use warnings;

sub countIt
{
    my $data = shift;
    my $lines =()= $data =~ /\n/g;
    $lines++ unless $data =~ /\n$/;  # Last line may not have \n on it
    my $words =()= $data =~ /\w+/g;
    my $length = length($data);
    return ($lines, $words, $length);
}

print join ',', countIt("  Blah blah blah\nStuff-by:somebody");
[download]

#Prints 2,6,34