What does Undecided really mean?

Alert Reader sends in this quote:

How will undecideds vote on election day? Traditionally, there have been two schools of thought about how undecideds in trial heat match-ups will divide up at the ballot box. One is that they will break equally; the other, that they will split in proportion to poll respondents who stated a candidate preference. But our analysis of 155 polls reveals that, in races that include an incumbent, the traditional answers are wrong. Over 80% of the time, most or all of the undecideds voted for the challenger.(...)

Link to full story and backup statistics

Now, that's great news for Kerry, of course. But how about our Senate race? Does Carson have the onus, on the basis that he is currently holding office in the House? Or Coburn, because he is the Republican candidate running for a Republican seat?

Guess you can add one more thing that Carson can't take for granted.