There are two reasons to go short as I see it....

One is because you think/expect the PPS to crater, and you want to profit from the fall.  If confidence is very high, like you have some information that a trial is going to be halted or something like that, then you're going to want to short as many as you can get your hands on and sell that at the highest possible price.

The second is that you want to scare shareholders into selling so that you can accumulate the shares being sold due to the fear, uncertainty and doubt that's caused by a falling share price....in this second case you're not looking to short ''as many as you can get  your hands on''....just enough to push the price lower, dumping on every uptick.  This is commonly referred to as ''Shaking The Tree''.  

I think we saw the 2nd of the two expamples take place between the 31st of May and 15th of June....when short interest exploded higher from 200+K to over 800K.