McGrath isn’t a bad candidate because she’s “too centrist”, she’s a bad candidate because she’s gaffe-prone, a grifter, and an empty suit who shows little consistency in her views. Believe it or not, most voters don’t decide who to vote for based on their handy-dandy “centrist calculator”, and sometimes the more progressive candidate also happens to be the better candidate, even if the race isn’t really winnable for either candidate.
Maybe, just maybe, they don't need the calculator because oftentimes "centrist" politics (which usually is just a euphemism for corporate corruption anyway) correspond to a PR-obsessed persona, lack of articulable values or morals, a willingness to do or say anything to get elected, etc.
Everything about Amy McGrath, John Hickenlooper, Ossoff, MJ Hegar, Cunningham, etc. feels contrived. I actually happen to know Hick, and can tell you that IRL he is not this friendly soap salesman act he puts on. He's a mean drunk with a penchant for saying abusive things to his staffers and living a bit more luxuriously than someone of his station probably should. But he also is willing to be whomever donors/Schumer/the party tells him to be in public in order to seek the office that he desires, because it's all about him and he doesn't care at all about anybody else, let alone working people.
I think this kind of vapidity is highly visible for those with eyes to see, and Amy "pro Trump" McGrath exemplifies it too, albeit to a lesser degree. Eventually, these DSCC lapdogs won't be able to make it through primaries anyway, and it will all be revealed the whole time that corporatists puppets were, in fact, less electable.