Mike Trout turns 21 on Aug. 7. Here is a look at how some other players fared entering seasons in which they were 20:
YEAR PLAYER RUNS AVG. HRs RBIs
1951 Willie Mays 59 .274 20 68
1952 Mickey Mantle 94 .311 23 87
1954 Hank Aaron 58 .280 13 69
1990 Ken Griffey Jr. 91 .300 22 80
1996 Alex Rodriguez 141 .358 36 123
