Mattingly in his prime is a no brainer. If you have to roll the dice and get a random year then you go with Hernandez. But there's no doubt to me if you had either guy at his best you'd have to go for Mattingly...
Hernandez also had 1000+ walks compared to a little under 600 for Mattingly to go with the hits/avgs. And had 2 more gold gloves plus a batting title in his 3-year longer career. Statistically, they are actually pretty even. I give my edge to Hernandez due to the aggressive way he played first base (and still won gold gloves), his leadership, and ability to dissect a game second by second and translate that to his teammates.
That ... and Mattingly was f'n Yankee Seriously, though, Keith was one of my favorite players before he ever came to the Mets.
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1964 - 2008
"And from what I heard, he had a good time, other than getting punched in the head.” - Cael Sanderson regarding Randy Couture
I agree with Gantry's assessment. Hernandez was never considered the very best player in the game, as was Donny Baseball.
That said, Hernandez was likely the best fielding 1b ever, despite the disparity in fielding percentages. His defense was so good it could be considered a weapon. He had a massive OBP and was an excellent contact hitter. I wonder if his career might've been even better if he had laid off the nose candy.
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Mother Teresa and Gandhi are the equivalent of poo when comparing their humanitarian behavior with the legendary Jazzerton Boxwell "Dana" White.