well, that's the whole purpose of a tumbling service. i mean you don't even know how long they will be stuck there. i didn't investigate this, but splitting those into small amounts and then tumbling these around seems like exactly this pattern. if you are interested on how this was done in the maybe now second biggest known btc heist check http://www.newstatesman.com/future-proof/2013/12/theres-£60m...
Can we verify this? Obviously we can't trace the outputs, but can we look for patterns that suggest the use of tumblers/mixers?