"DROP"
it is quite difficult to master the "drop" because weight is treated scientifically (plus the fact that the risk of playing wrong notes is higher since it's not close to the keys).
one should know how to control the dropping, or the distance of the hands from the keys before dropping in order to achieve different sounds. fingerings of chords are important. the opening chord (c minor 1st inversion for the RH) of the pathetique sonata by beethoven should be fingered as 2-1-5 (Eb-G-C) when doing the "drop". this will automatically voice your top note because when the thumb is under the 2nd finger, the whole weight of your hand shifts to the 5th, thus your top note is given more weight.
i had the privelege of a few lessons with Dr. jose Maceda (check grove's) before he died 3 years ago, who studied with alfred cortot. dr. maceda uses this technique. everything is about weight, he says.
i observed the way he would drop and the wrist does not bend much.
sometimes a forward motion of the arm is noticed.
single-note melodies he would drop one by one like in the chopin Eb nocturne (he doesn't connect much, if tolerable). he uses the pedal really well. the opening of Chopin Barcarolle is like gold in his hands!
i think i remember him saying about the thumb being very important... i forgot how?

the main theme of the schumann concerto 1st movement works really well with dropping. playing it at p level using the "drop" will fill a big hall with nice caressing tones.. plus of course voicing the top notes.
WEIGHT=PRESSURE
scientific use of weight is also applicable to running passages and certain hand positions and weird fingerings are used in playing certain phrasings. good planning of the weight shifting and the fingering will automatically do the kind of phrasing you want. but sheesh, those fingerings he taught me were WEIRD. it's only now that i am able to understand its logic, after 3 years.
i never learned it coz he was the only one who could have taught it here in my country.