the ecu tune file and tear down of the engine is the only thing that will tell you what went wrong.
On another note i have a good customer with a engine i built for him 8k worth of SR, i get a call from him @ a comp in Tassie saying its running on 3 and its f**ked..... says its pinging so bad (a so called expert @ he track diagnosed it) it closed a plug gap... i explained thats impossible and only something hitting a plug can do that (expert @ track in background can be heard saying crap tune etc etc)... i told him to swap out the plug and see how it runs...
i then freak out for 3 days wondering how and why only to find out his new throttle body he installed himself had dropped a butterfly screw... and the engine subsequently ate it... this could have been a classic case of blame tuner first then find facts later
Lucky this customer did not get all high and mighty when it did happen and listened to reason and subsequently found the issue himself a few days later, often it is hard to find the reason for failure without a thorough going over of the car.
If it is down in comp and breathing then yes it could be pinking or lean (tune related), if it spun a bearing chances are its an unrelated engine failure.