Yes. Callouses are created by friction and will show wear that is created by the swing and release pressure or squeezing. Callouses show normal wear, as well as improper wear. If you look at average bowlers compared to most exempt pros, you would see a drastic difference.
No matter what, a bowler will create callouses. If callouses are created by blistering, generally they are from either an improper fit or a bad release, created by bad timing.
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