The betting markets reflect the weight of money and the consensus of punters. If big money came in for Guy the odds would change a lot. It is not as predictive as an actual poll. Punters are looking at the polls and backing Andrews to the point he has Roger Federer odds.
The polls should tighten a little more, and Andrews may do something stupid or vice versa. Reality is there is a lot of closeted disapproval of Andrews and resignation and the result. Most are not enthusiastic about Andrews winning, more that he is the best choice of a bad selection. Just look at the story recently about the CFMU worksite posters calling Dan a "prick", but to still vote for him.