You're slurping the entire file into an array:

open(INPUT, $infile);
 my @lines = <INPUT>;
 close(INPUT);
[download]

Which means by the time you reach where I loaded the header line:

my @headers = split ' ', do{ my $raw = <INPUT>; $raw =~ tr[",][ ]; $ra
+w }; #"
[download]

There is nothing left to read.

Either shift the first line off of the array:

my @headers = split ' ', do{ my $raw = shift @lines; $raw =~ tr[",][ ]
+; $raw }; #"
[download]

Or don't slurp the file and revert to using while.