In terms of actual importance in Baseball, Curt Flood is in the top ten, if not top five in the game.
The story of Howard Ellsworth "Smoky Joe" Wood is typical in that and we have a power pitcher who was dominant for a short time, only for arm fatigue to cause an early end of his pitching career (though he would continue to play, but we'll get to that later.)
Ted Kluszewski was a monster in his day. This was not just in regards to his tape measure Home Runs, but that he was such an imposing physical specimen that he cut off the sleeves of his uniform so that his arms could better move.
One of the most popular players in Cleveland Indians' history, Rocco "Rocky" Colavito, came from the Bronx, where naturally, he was a Yankees fan.