This method invokes an on-the-fly subroutine with the string split into characters as the arguments. This allows you to shift groups of three letters at a time using a map, with a second map to do the subtraction, all inside an array ref. constructor which is pushed onto the return array.

use strict;
use warnings;

my $string =
   q{BEHACJBDLCENADFEGOFHQAGIHJRBIKJLSCKMLNTDMOFNPOQTGPRIQSKRTMPS};

my @array  = sub
   {
       my @arr = ( [] );
       push @arr,
          [ map ord( $_ ) - 64, map shift, 1 .. 3 ]
          while @_;
       return @arr;
   }->( split m{}, $string );

printf qq{%02d %02d %02d\n}, @$_ for @array[ 1 .. $#array ];
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The results match yours and I think the numbers may very well have something to do with the England cricketer's recent batting form :-(

Cheers,

JohnGG