First I'll re-word the question.
Have the balls in the last 4 years really gotten better due to improvements to core and coverstock's? or is the "New 'N Improved" just a marketing gimmick? If not a gimmick, How much more can core and coverstock's improvements go?
It would all depend on what you mean by "Gotten better" Do they hook more? Do they have stronger reaction's to lane conditions now verses the past? etc.
Sure there are a lot of marketing gimmicks used to promote balls, "Our new core does this" "Our new coverstock does that".
Yes ball tech has improved/changed over the years. They match cores to coverstock's better, longevity and durability, oil absorption, friction and flare properties etc. have kept pace with bowlers needs and wants. That doesn't mean the older balls won't work, just they will work differently.
Can they keep improving? Depends on what is meant by improve? Well can the hook more? Sure! they can already make balls that can hook right off the lane.
That's what fueled the particle ball craze, till they realized that ball's that hooked that hard. Were so limited in usage they now have all but disappeared.
What Future improvements can be made in balls? It will all depend on what the bowler's want or think they want.
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