The timing is definitely a good factor for Biden - a 1-2-3 push days before voting. There are a lot of votes already cast, of course, but still, it's a good media earner and momentum booster. I suppose Warren did him a huge favor by goring Bloomberg on national television the way she did. If not for that I think Bloomberg may have been the main rival to Bernie, even with SC.
(speaking of SC, I read that Michael Moore was on MSNBC yet again whining about how South Carolina voters are not representative of America - not so subtle coding going on there from someone who was last relevant in 2004, and didn't even deserve to be relevant then).