Certianly a good proshop 0perator can drill a ball that can significantly improve many bowlers average by matching the ball up to the bowler. However, this ball my work for a specific condition, it does nothing to help you on other conditions. And then there is the contention that this is why you need more equipement to match up to different conditions. But with this contention comes the knowledge of understanding the conditions and when to use a specific layout. This is where a good coach comes into play. Understanding what is happening on the lane surface and how different balls (layouts) can take advantage of the condition. As well coaches provide information for what I term "tricks" that can be used to fine tune ball reactions.
So in short, the easiest thing is to drill new equipment however this usually has a limited improvement on a specific condition. Getting good coaching lasts a lifetime and makes you better on all conditions.
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