Before you even consider strobbing basketball make sure that you are insured!
when shooting with flashes, you rely on the flash duration of the lights to stop the action
letting in ambient light while shooting with the flashes will result in blur and/or ghosting (like you got)
this means that your exposure without the flashes should leave the frame completely or almost completely black (the more ambient, the more blur)
With the speedlights those shadows and harsh light ("flashed" look) are pretty much unavoidable, as the light will not have enough power to bounce. You can get softer light by using a strobe and bouncing it.