my @old = ('74/05/25', '54/03/04', '69/08/23', '55/08/24');
my @new = map { join('/', ( split('/') )[1,2,0]) } @old;

Produces:
old: 74/05/25 new: 05/25/74
old: 54/03/04 new: 03/04/54
old: 69/08/23 new: 08/23/69
old: 55/08/24 new: 08/24/55