I believe very large ships like this have to start slowing down maybe 20 miles or more out , same time when they enter a port or canal they absolutely have to maintain a minimum forward speed or the effects of wind and tide can very easily become very unpredictable . I guess no one apart from the people up on the bridge that day really know what happened .
I remember in the olden days boating in the local estuary ,it took a bit of time to learn helmsmanship , initially people tended to over correct wildly and cut a zig zag path through the water , after a while you learn to apply corrections little and often, of course a little boat is quite forgiving where 220,000 tonnes isnt. Id expect nowadays with ship simulators pilots are probably better trained than ever before , still accidents happen .