The "small state problem", however, doesn't change just because Democrats run better candidates. And I'm not even saying the senate should be made up differently, even though Puerto Rico and DC should be granted statehood.
Running better candidates is only part of the story (Gideon really isn’t that strong, I’d say). The biggest problem is Trump/Republican voters simply being much more likely to split their ticket/elect a Senator from the other party than Democratic voters.
There’s no way a Republican equivalent of Jason Kander or Doug Jones would have even kept it close. Heck, Hugin who ran against a scumbag barely did better than Trump, and Republicans couldn’t even hold NH-SEN 2016 where Clinton lost by less than .5%.
Baker won his last election with a lead of 33 points. He would not win a Senate seat in the Trump era, but with Biden in office, he’s a decent comparison to Kander.
Jones is a special case and will lose badly this November. Menendez is scum, but the electorate has long been more forgiving of the corrupt than sexual predators.