Ok, maybe i'm reading wrong, but on Arreat summit (The battle.net site) it says...

Speed of Grand Matron +10
Speed of Hydra +10
Speed of Matriach -10

Now, this is all good and well, but Why does it list ballista's speed as -70? Obviously ballista is not faster than WF or Mav's Bow. So are they on a different scale? Everyone tells me matriach is the fastest bow, things aren't adding up here cuz matriach has a lower "speed #" than Hydra....

I'm very very confused, can someone please explain that to me?