From the current evidence on PPRuNe there is a good possibility that the cause of the Lion Air accident will be found to be the failure of the captain to conduct a safe go-around after losing all forward vision due heavy rain at or below the MDA. Where the actions of his first officer will come into the equation, has yet to be revealed.
It has been suggested
in this thread from 'inside information' that the F/O retracted the flaps to 15 degrees without being commanded by the Captain, who we assume was now the PF. If that's not a failure in CRM, or Multi-Crew Coordination, then I don't know what is.