It certainly wasn't a landslide (4%) but Joe Manchin won reelection.
What did the exit polls find?
The Manchin-Morrisey election was decided by voters 39 and under, said professional pollster Rex Repass. Manchin won 60 percent of these voters, according to exit polling by Edison Research.
In all other age categories, the vote was essentially a tie.
Repass also noted that, despite Trump's frequent visits in support of Morrisey, Manchin was still able to get 30% of those who voted for Trump.
Additionally, an ABC News exit poll found Manchin with a much higher favorability rating.
What about pundits?
Here's Hoppy Kerchival's analysis at WV Metro News:
The big picture answer to his success is that Manchin has, over the years, established his own political brand. His political identity is not that of a Democrat, but rather as the “party” of Joe Manchin. West Virginian’s know him. Not everyone trusts him or even likes him, but he has built a comfort level with enough voters to carry him across the line in a tough election.
And as both exit polls found, Kerchival thought Manchin's vote for Brett Kavanaugh was also important.
While the national media certainly reported Manchin winning, not many looked at the "why?" Ken Silverstein at Forbes similarly argued that Manchin is his own brand but also noted that he has established a long-term relationship with the workers in the state, especially working and retired miners. As for Morrisey, Silverstein argues that he is living in the past:
Morrisey kept hyping Hillary Clinton’s misspoken words about putting coal miners out of work — a quote that in context was meant to convince the state to invest in the future because the national economy was evolving and using cleaner fuels. Morrisey, in fact, seemed to focus on the past — trying to ensure West Virginians that coal could remain their lifeblood if only he would be elected.
I'd certainly agree with the above. Additionally, I think Morrisey ran a horrible campaign with little imagination and few proposals. Morrisey's campaign essentially consisted of wrapping himself around Trump and attacking "lying, liberal Joe" while connecting him to Hillary, Obama and Schumer. I also think his connections to drug manufacturers and his lawsuit against Obamacare hurt. The emphasis on both of these points in Manchin and Manchin-supporting PAC commercials worked well for Joe. Manchin's commercials also looked to be better targeted and more professionally produced. On the other hand, Morrisey often looked uncomfortable in his ads -- probably no more so than in his commercial addressing workers where his concluding "Amen, brothers" sounded as out-of-place as the hard hat he was wearing looked.
Earlier today, Manchin did his victory lap appearing on the "CBS Morning News" and MSNBC's "Morning Joe."