Okay, maybe I misread, but:
And "slow, painful, gradual" is the opposite of what you appear to have said here.
So, help a fellow historian out - what are you trying to say here?
Steep decline dosnt mean instantly. It means that over that can be an extended period of time that rebellions increase ( that they did) and persia's influence was actually quite quickly replaced by greek influence. After salmeis we see greek mercanaries, artists,diplomats being exported all over the world, with greece becoming an internatiional language of diplomacy. Persia meanwhile, and the idea of being part of the persian empire suddenly was replaced by the individual subject nations view of themselves.
I think the maybe the main misunderstanding here was are different interpratation of " steep decline," you see it as a fast phenomanom, i see it as a slower process. Sorry for any confusion!