Al Simmons joined the Philadelphia Athletics when he was acquired from Milwaukee of the American Association before the 1924 Season.  He would have a great rookie season with 183 Hits and a .308 Batting Average, so it was clear that he was a good hitter, but what he would do afterward would make his first year in the Majors look, pedestrian.

Signed in 1901, Eddie Plank would have a good rookie season for the Philadelphia Athletics, where he won 17 Games.  That is a good number, but it would take seven seasons before he had anything lower than that.

Jimmie Foxx was signed by the Philadelphia Athletics as a teen in 1925, and he would emerge as one of the most lethal power hitters in not just Athletic history but that of all of Baseball.

Rickey Henderson is a lot of things.  He is eccentric.  He often refers to himself in the third person.  He is the greatest leadoff hitter ever.  He is the ultimate base stealer.  He was a first ballot Hall of Famer.