I find that a period of weight training mid way through the amateur season is a huge crutch.

I find if I neglect weight training my arms become a bit "undisciplined" in combination. Where as if I do some weights they seem to move as fast but in a better textbook form.

I find If I work my arms that it has no effect on flexability or speed as they come from the movement of the core and hips, legs etc.

I no longer do weight on my legs, I merely run farther than before.

I perform some weight training that is directed at my abdomen with pulleys etc and I find it beneficial for power and sometimes balance.