Considering it was designed and hosted by IBM who are trying to recreate themselves as a primarily cloud PaaS company (see IBM BlueMix), I'd say it was a matter of IBM's engineers poorly configuring the scalability of the deployment, which I think also reflects poorly on their ability to service the cloud hosting market.
ABS shouldn't have outsourced the entire project to IBM, they could have just developed the application in-house and deployed it to an autoscaling CE instance group on Google Cloud, they probably would have saved $7-8 million paid to IBM while also avoiding this catastrophic failure.