my @list = qw(M4568-51 M4568-5 M8954-89 M4568-56 H1234-6 H0012-45);
my @big = map {
    m/^(\w)(\d{4})-(\d{1,2})$/ or die "bad data: $!\n";
    [$_, $1, $2, $3];
  } @list;

print Dumper(@big);

----------------------results (tidied up a bit)-------

$VAR1 = ['M4568-51', 'M', '4568', '51'];
$VAR2 = ['M4568-5',  'M', '4568', '5' ];
$VAR3 = ['M8954-89', 'M', '8954', '89'];
$VAR4 = ['M4568-56', 'M', '4568', '56'];
$VAR5 = ['H1234-6',  'H', '1234', '6' ];
$VAR6 = ['H0012-45', 'H', '0012', '45'];