Originally Posted by steenkash
2. Drop shots are only effective during long rallies, where it is so unexpected.
No way. They are just as effective early on in rallies especially if you've just had a couple of long ones or you're on-serve and you can force your opponent into reactionary mode from behind the baseline.
Federer couldn't get Murray into this mode enough at the Aussie Open because he was hitting too poorly generally and serving too poorly - that's why he wasn't making the right decision time-wise with them.