Good Drama ...Ehh Female lead

There have been some good dramas. Well written and well enjoyed, but there was something missing. The male character was impressive and you cannot get this character out of your thoughts. The male actor did a phenomenal job, however the female lead left a 'ehh' in your mind. You think back and say I wonder if the drama would be better if the female lead was played by another actress (one who is better at acting).