This was very informative as i did learn some things. But i was looking for the comparison of ball motion and hook potential on today's dryer conditions that bowlers face when reactives are out of play.

Generally speaking, from weakest to strongest:
Rubber, plastic, urethane, reactive.

Also, on older balls, softness/hardness may be a consideration.  They instituted the hardness rule after the Sur-D, I believe, so before that rule you may find some older balls with softness below the current limit and you may find some balls with very high hardness ratings.

I really need to get my old Hard rubber Ace Pro drilled just to see if I can hook it at all. My old Ace Plastic ball did have some weight to it and with a bit of roughing up I could get it to hook pretty well, even swing it a bit if it was really dry. I've actually never thrown a true Urethane but I may buy one for the hell of it once to try it out, I love drilling and throwing old equipment.

My suggestion to is if you want to get an idea of the different era's is to check out youtube. Just type in Dick Weber and then go from there. There are matches going back as far as the 50's on there. Just work your way up the decades and you will see the change.

One of my other favorites is Pete Weber's first televised match. He was 17 at the time and I believe he would of be been throwing Urethane although I could be wrong and it was still plastic. Basically anything prior to 91 would be the non reactive stuff.