Thanks, that's a lot clearer. To sort in descending order, simply replace $a with $b and $b with $a; e.g. in place of { $a->[3] <=> $b->[3] }, use { $b->[3] <=> $a->[3] }.

I hope your $created's are actual numbers, not strings as you show. If you actually have strings in your data, you are going to have to parse them further, since they won't be easily comparable as is.