Too late for me to think of some examples, and Im sure if this thread gets going there will be MANY, but who's better than Jared Goff in terms of this question? He looked like the worst QB to ever throw a pass in the NFL last season and now he's a legit MVP candidate. (I still think he secretly sucks, can't forget last year that easily)

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Fare you well, fare you well
I love you more than words can tell
Listen to the river sing sweet songs
To rock my soul

Mike Trout had a rough first year, though technically didn't have enough plate appearances to qualify as a rookie.

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312player

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Sex isn't dirty, sex isn't a crime. It's a loving act between two or more consenting adults.

-Hank Kingsley

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Yea, that was a 1/4 of a season.

There are numerous example of pitchers.


Greg Maddux first full season: 6-14, 5.61 ERA
Second season: 18-8, 3.18 ERA

Jimmy Graham.

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“When I walked in this morning, and saw the flag was at half mast, I thought 'alright another bureaucrat ate it.'" - Ron Swanson

Jay Williams

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Anthony Rizzo (This isn't true, but it was nice to see as a Cubs fan)

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Rick Hahn is the best GM in baseball.

Larry Nance is one that always comes to mind.