All-Star Ballot question

[CarriageTownBaseball]

Found lots of reddit threads on this but none address my question. I'm curious how the game chooses who is on the AS ballot. I had two guys vying for a utility position, so I had both playing regularly at 2B and SS during spring training. The last day of spring training, I set my regular roster and lineups. All star ballot comes out and my back-up, a rule 5 guy with about 30 PAs and a .120 batting average is on the ballot as 2B from my team, and NOT the guy who won MVP 2 years ago and has been my starting 2B for about 6 years. He's made all but 4 starts at 2B this season, but not on ballot. Same for my SS (who is having a career year). I have NO player at SS. All the threads are about how it's based on popularity (were that true BOTH of my starters would be on that ballot as BOTH are extremely popular). Seems like the game is building the AS ballot from spring training lineups which seems, well, wrong.

I know I can manually select all-stars, but that's not a great option, either. Seems like it would make sense to either a) have the manager nominate players from his roster to appear on the ballot, and/or, b) allow the manager to correct a mistake on the ballot. There are numerous players not even on an active roster showing up on the ballot. Yeah, that could happen in the case of an injury, but there are at least a half dozen AL players like that on my ballot, and several NL, as well. Something isn't right, here.