Forward reverse tends to define the holding power one has in the ball in relation to your span.

The "table" standards from Bill Taylor indicate 0 forward reverse for a 4 1/4 span.

More reverse if the span is longer by each 1/8 add 1/16 reverse.
More forward if the span is shorter by each 1/8 shorter add 1/16 forward.

Those that drop usually go 1/8 forward of these tables.

Also a loose thumb causes dropping.  Too much bevel in front dropping.  Urethane leads to a faster release and vinyl to a slower release of the thumb.

AND MOST of all!  A good coach recently told me.
"If you are anywhere close to the right pitches....late timing causes dropping above all other things."  "Fix the timing and then tweak your pitches"

REgards,

Luckylefty