So why is Mastriano being so closely tied to Trump a bad thing in PA?

[Southern Senator North Carolina Yankee]

A lot of the hangers on who like to mold themselves in Trump's image, botch it horribly. Many of them are former Ted Cruz style Tea Party types and thus the last people capable of pulling off what Trump did for the simple fact that for some of Trump's voters, Trump was a reaction against the politics of the tea party era.

[I spent the winter writing songs about getting better]

Here's something else that I think isn't being discussed: The national environment doesn't impact Gubernatorial elections anywhere near as much as others. I'm not saying it doesn't at all obviously, but look at 2018: The Democrats only defeated two incumbent Governors, Bill Rauner and Scott Walker. One was a total fluke who only got elected because of the insane unpopularity of his predecessor (although he probably could've gotten re-elected had he not alienated everyone ala Larry Hogan) and the other was probably the single most hated Governor in the country by the opposing party's base, and even he just barely lost. I suppose technically Bill Walker also lost as an incumbent, but if you count him that just proves the point even more since that was a Republican pickup in a D wave year. Now of course there's no incumbent in this election but in terms of open seats the Democrats picked up Nevada, Maine, Michigan and Kansas. Now that's impressive don't get me wrong, but two of those were Hillary states (and despite that Nevada was still pretty close), Michigan had a pretty solid candidate against a weak one connected to a sort of scandal-ridden predecessor administration, and Kansas has already been covered with a Mastriano-like candidate. Now the national environment might've been needed to pull Evers (and maybe even Sisolak) across the finish line but that just shows that it was the deciding factor in a tossup race and not solely responsible.

In fact Pennsylvania itself proved its willingness to buck national trends when it was the only Democratic gubernatorial pickup in 2014 (unless you count Alaska), and it wasn't even close either. And yes, you could say that's only because Corbett was so personally unpopular...but that's exactly the case with Mastriano as well. So the evidence we have despite ElectionsGuy just constantly raving about the national environment over and over is a really unpopular and weak candidate can still flop in such an environment. If Shapiro had his own flaws to the point where you'd argue that Shapiro/Mastriano would be a toss-up in a neutral environment then yes the national environment could be enough to push Mastriano over just like Tony Evers, but there's no evidence that's the case.

[I spent the winter writing songs about getting better]

Because it made him a garbage candidate that's why.