"Offensively, the things he has done is what guys who go on to be ten-time All-Stars and Hall of Famers do."
See Theo Epstein Loves Starlin Castro and Other Bullets at "Bleacher Nation."
The list below shows all 2B-SS who had 500+ PAs through the age of 21 and their OPS+.
He is close to two Hall of Famers, Alomar and Ripken. He has done better so far than two frequent All-Stars, Whitaker and Randolph. But Delino DeShields and Gregg Jeffries did better and are not in the Hall and Jeffries had just two All-Star teams.
Here are three SS he is ahead of who made the Hall:
Travis Jackson 92
Robin Yount 86
Rabbit Maranville 78