Unless a candidate can poll 50%+, these mean nothing. After Iowa and New Hampshire, one or two “Not Bidens” will be chosen. My guess is that Sanders and an identity pick (combination of black/homosexual/female) will come in. Biden’s job will be to keep the white Sanders supporters with Sanders rather than joining a minority socialist campaign.
Flame-outs will be Beto and Buttgieg, who may stay in to control a bloc of delegates if no candidate gets a majority. He will also swim in money. Normally I would write off Warren, except I remember when John Kerry was left for dead and wound up being the last man standing.
Things like money and endorsements and staff follow the polls, too.
Iowa is an expensive state to campaign in, you need to figure out the whole caucus system, which means hiring someone, and then outreaching to precinct level people. There are probably not 20 political operatives who know the blocking and tackling well enough to get a decent finish there.
Jay Inslee, for instance. Would a top Iowa campaign guy go work for him this week?