In evaluating how this year's rookie class might do in the future, it can be helpful to reflect on the winners of the Rookie of the Year awards. The National League has had great winners, dating back to Buster Posey in 2010. The American League has had great winners, dating back to Mike Trout in 2012. Each league is riding a hot streak, with tremendous young talent emerging and then sticking around. The very best rookies have made their leagues even stronger.
At the same time, not every good rookie stays so good. There's a misconception that young players only get better and better. Consider the cases of Aledmys Diaz, Trevor Story and Tyler Naquin. Talented ballplayers, all of them, but compared with their 2016 seasons, 2017 was rather humbling. Some players peak when they're still very young. Some players' improvement doesn't follow a linear progression.
So how are this year's best rookies going to come back in 2018? How are some of the other top performers going to come back in 2018? I've selected 10 high-performing rookies, and I've placed them into three groups. In the first group are players I think will remain at least as good. In the next group are players I think will decline, while still remaining valuable. And then there's the last group, comprised of players I think might've peaked. Let's look back on -- and ahead for -- some eye-opening performers.