Broken Torque Convertor hub. What would cause that.

[Blacksdieselhp]

A friend of mine has a 2005 truck that is doing around 600 hp and the truck has built transmission with a triple disc convertor. He pulled the transmission to fix an oil leak at the rear seal. When he pulled the tc off of the input shaft, he noticed the hub of the tc was broken and a big chunk of it was still stuck in the transmission. Anyway, he had to have the truck and didn't have time to send it back, so he put it back together and was carefull to line the tc back up where the broken piece fit into place. Just wandering what could cause this and what kind of damage it will do by running it like that. The truck has a smarty/tst stack along with several other mods, but I kindof figured the aggressive bottom end of the smarty may have caused it. Any thoughts?