It never had more than a few thousand BTC (except for a few peaks) at any point in time. [1]
[1] - https://blockchain.info/charts/balance?address=1Drt3c8pSdrky...
[1] - https://blockchain.info/charts/balance?address=1Drt3c8pSdrky...
According to Gox, the theft was happening over a long period of time, not one lump sum. Transfers to this address began in April of 2012, which is consistent with the story.
I don't think this has anything to do with it, it should be easy to determine if the transaction are linked to MtGox and malled tx's