It looks to me more likely the problem was excessive weight at the bow and stern rather then midships, the effect is called hogging and is a known way to snap a container ship (or oil tanker) in half, both have occured in the past.
Basically the keel (The BIG beam running all the way from bow to stern down the bottom of the hull) can only take so much sheer stress and if the weight distribution does not match the localised boyancy implied by the current displacement you can very easily bend the ship.
When I first saw the phrase "severe hogging" first thing I thought was a reference to overloading (hogging the weight ones allowed) ie: being overweight.
Figure it came from reading the summery first, so I checked it out here's a PDF named Container Ships http://preview.tinyurl.com/ogy89e8
Page 8 shows Hogging and it's opposite sagging, now sagging I could of understood.
A nasty accident, but nobody died, and the hull and cargo will have been insured, so a better outcome then is sometimes the case.
From the PDF in the Summery, on the The cost of losing a week
"In a recent Maersk Line survey, one global retailer explained that 70% of his cargo loses on average 25% of its retail value when it is a week late. With an average cargo value per container of EUR 30,000, the cost of delay equals EUR 7,500 per container."
goes on to say electronics lose even more, had to calculate a value on should of's...
Hope that explains why it is not just about total weight.
If I'd of taken the time to of read