Herman Cain's Positively Negative Trendline

FiveThirtyEight had this little graph and the comment. "It looks to me as if Mr. Cain had been on a positive trajectory before, perhaps having moved up to about 28 percent of the Republican vote.

Really? You see an upward trend there? Is that blue trendline all that reasonable?

I see a downward trend if I get rid of the first week's data.  If I include the first week, then I can see that blue line being the calculated trendline but it should be obvious that the bump he received on Oct 8th (appearance on Huckabee, touting his 999 plan?) brought him to a plateau and he's been losing ground ever since. The allegations didn't change that downward trend.