 Wilhelm was one of eleven children born to poor tenant farmers John and <unk> ( née Stanley ) Wilhelm in <unk> , North Carolina . He played baseball at Cornelius High School in Cornelius , North Carolina . There , he began experimenting with a knuckleball after reading about pitcher Dutch Leonard . He felt that , because he could not throw fast , <unk> a knuckleball offered him his best shot at success . He used a tennis ball to practice . 
