I believe you were wrong. It was a single sell order that caused the crash.

I wrote a bit about it here:

https://steemit.com/ethereum/@ccampbell/my-theory-about-what-happened-on-coinbase-gdax-today

Some people suspect it came from this wallet:
https://etherscan.io/address/0x7d551397f79a2988b064afd0efebee802c7721bc