http://www.buddiesproshop.com/136/Wh...09_Season.html
I have seen some of them even throws backup ball for sparing. They doesn’t use plastic ball much now. Are they confident with their shots? Or reactive balls are just getting better with anything?
Either the spares have a higher chance of being spared if they back-up and if they use their strikes for spares on the that should be cause the pins left are on their left side for right handers and right side for left handles.
Other than that pretty much all the spares done by pros i've seen use normal plastic balls or high friction balls (which i'm not sure if they are reactive a not)
So if i'm wrong or you think i'm a wannabe please just tell me so I can learn new stuff :)