The answer is there is no definite answer that applies to every ball. Every ball has varying coverstocks, core shapes, core densities, and varying mixtures within the filler material. There are lots of reasons that can cause a ball to crack.
A few years ago one particular batch of balls had too much air in the filler material mixture. As the filler material started to crumble and slowly leak out of the thumb and finger holes there was less to support the coverstock, and eventually that manufacturer had balls cracking at a much higher percentage than normal.
This is just one example. There could be a miriad of reasons as to why one ball cracks while another one doesn't.
Lane Carter, Strike Zone Pro Shops - Salt Lake City, Utah
Brunswick Pro Shop Staff
www.brunswickbowling.comThe opinions expressed are solely those of the writer and not of Brunswick Corporation.