Posnanski has an article with some great background about the lack of a unanimous yes vote, and why that should end with this year's class. (sub req) snippet: Four schmoes don’t vote for Cobb? The BBWAA screws up the DiMaggio vote? A few writers for odd, unknown, probably petty reasons don’t vote for Musial, Mays or Aaron, Ripken, Griffey or Maddux? This isn’t a tradition. No, it’s an accident of randomness, negligence, stupidity and personal vendettas. https://theathletic.com/733813/2018/12/26/posnanski-how-the-lack-of-hall-of-fame-unanimity-became-a-thing-and-why-it-should-end-with-mariano-rivera