Harper got his first taste of big league action for the Nationals on Saturday at just 19 years old. There's been plenty of speculation as to when Harper would finally get a call-up, and the Nats decided to pull the trigger when Ryan Zimmerman hit the disabled list.
Major League teams are faced with tough decisions every day, but deciding when to bring a player up is perhaps the most difficult, as doing so too early can hinder the player's development. The Nationals hope that isn't the case with Harper, but he undoubtedly has the talent to succeed in the bigs right away.
Harper's call-up got us thinking, though. Which other players throughout baseball history have arrived to the majors prior to their 20th birthday and immediately made an impact?
Ken Griffey Jr. is a recent example that comes to mind, while Mel Ott is a name you have to go way back to remember. Either way, both succeeded as teenagers, but they're not the only ones.
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