How good an athlete was Jackie Jensen? He was the first person to play in the Rose Bowl, a World Series, and an MLB All-Star Game.
Josh Beckett would take the Florida Marlins to the 2003 World Series Championship and would win the World Series MVP along the way.
Mo Vaughn was one of the ultimate one-dimensional power guys, but if that is going to be your skill, you might as well be good at that. Vaughn was exceptional in that skill.
A member of the Boston Red Sox for all but his final season (2002), John Valentin was one of the better defensive players in Red Sox history.