Well, a few things.
1) The trendline was toward Manchin in the final week of 2010, it is against him in the final week of 2018.
2) Raese was a toxic candidate, far worse than Morrisey.
3) Raese didn't have WV's God Emperor enthusiastically supporting and holding rallies for him.
And most importantly:
4) 2010 was before a majority of West Virginia voters began to see all Democrats as irredeemable members of an anti-white hate group. The line of demarcation for this shifting of the paradigm was on November 7th, 2012. One day after Manchin was last on the ballot!
Morrisey is not a good candidate, lol. Let's look at some other differences.
1. 2010 was a GOP wave year.
2. The Democrats just elected a governor in 2016, he overpeformed Clinton by over 40 points as well. It doesn't matter if he is a republican now, he RAN as a democrat.
3. In 2010, there were some public polls that showed Manchin losing in the last month or so. The only poll we've seen with Manchin behind in this State in the past several months is......NRSC.