If you can believe it, Opening Day is only six weeks away. That means if we're going to start previewing the season division by division on a weekly basis -- and we are -- we have to start right now. Baseball is an individual sport masquerading as a team one, so we'll be previewing each division by counting down the 20 most pivotal players in the division. These aren't necessarily the best players. They're just the ones whose 2018 performance will be most vital to their team's success this season, and seasons moving forward. And to keep it balanced, we'll pick four from each team.