Why did the USBC ban bowling balls?

Why did the USBC ban bowling balls? It was March 29, shortly after the start of the USBC Masters, that USBC announced it had reached a deal with Storm Products that banned six bowling balls from USBC national tournaments because of hardness issues.

It was March 29, shortly after the start of the USBC Masters, that USBC announced it had reached a deal with Storm Products that banned six bowling balls from USBC national tournaments because of hardness issues.