Much of the fillies lack of success may be attributed to simple variance. Whether there was bad luck in running, lack of the best fillies running due to circumstances/conditions, due to running into a very above average colt or because simply there was a few down years for fillies. I won’t profess to know the exact answers, but saying "don’t back fillies" because of their bad record for awhile, or "back fillies, look at the past 5 years" is far too simplistic a view. You need to know why either of those may have merit to them.
