I've been on the rig floor of a floater. Have you? Even run tongs (chain as well as power). Have you?
Guess you haven't heard of heave compensation to account for the wave induced movement of the vessel/riser?
They did know there was more coming out than going in. Read the reports. They failed to react until it was too late. That does not excuse TO. TO is at fault for not training the crew. Nor does it relieve the companies responsible for BOP maintenance. But had the crew been properly trained, they would all be alive today.
I'm standing on a DA drillship right now and have been in this for 20yrs working for drilling contractors. I have time on the brake and in the cyber chair; admittedly in the resume you provided you don't. Lack of training had nothing to do with the psychological forces at work at that time, on that rig. Read more. All reports and even the court findings concluded the ROOT cause was the pressure put on the crews by BP (and reinforced by TOI). I understand you are an engineer and only see numbers.