According to MLB, a rookie is “A player who hasn’t accumulated 130 at-bats or 50 innings pitched in previous seasons and hasn’t spent 45 or more days on 25-man active rosters, not including times when the active list is expanded to 40.”
Most times rookies come out of nowhere and surprise his team and the league. rarely do you see a rookie start the season as a starter and nearly handed the rookie of the year award like they did with Jason Hayward, until Buster Posey showed up.
Nevertheless, I’ll hand hand someone the award anyway.