Surface is the largest effecter of ball reaction....you can smooth reaction by lowering surface
Secondly if bowling ball does not slow properly, the core/layout will not effect the desired reaction properly
Weight holes tend to effect reaction after the ball slows but also dependant on existing flare
One issue I see with layouts is they are not adjusted correctly using a weight hole-take a 1.5-2.5" pin to pap layout...more times than not a weight hole is not facilitated thus the flares stay tight creating a quicker response
Too many times, bowlers not understanding weight hole effect shy away improperly...weight holes make the ball hook earlier or more...not always nor only effect they have