There doesn't have to be "historical evidence". A popular governor in the most important, must win state that could be decided within 50k votes is simply a no brainer. If Harris loses PA, all narratives will point to who she didn't select as VP.
You've been very vocally content with the Walz pick, so why is it back to Shapiro being a no brainer? Either he's a no brainer, and all other picks are obviously wrong, or he isn't.