But Why?

I'm really not even taking sides here, but in very general terms, when journalists and Professional Democrats talk about the kind of person who they should run in swing states to appeal to more rural voters they describe a "Fetterman" (not specifically the guy, but the type), and then they deliver a "Lamb" and get confused when they don't win the primary or get wiped out in the election. 

Fetterman might be the weirdo long shot outsider candidate if he hadn't already won statewide office. But he did! He's Lieutenant Governor! He spent years working the whole state!

Lamb has had so much sympathetic press because people with rich backers get lots of sympathetic press! Fetterman was always the presumptive frontrunner, everyone else the challenger, and the media coverage constantly inverts this.

Big money (a lot and high average donations and PAC money) doesn't just buy paid media, it "buys" a lot of free media too, no matter how low you are in the polls.

The article isn't that objectionable except for playing up the "campaign was just too nice" nonsense when a Super PAC and surrogates were doing the dirty work, but where did this presumption that Lamb "had the makings of a Front-Runner" come from?

Except this:

Mr. Fetterman has made his lack of endorsements into a kind of badge of honor: He has long disdained glad-handing other elected officials and is an unpopular figure even in the statehouse, where he officially presides over the State Senate.

He's unpopular in the statehouse because it's run by Republicans, aside from his presiding role!