Since your including Pedro's 01 season, I'll include Koufax 62 season, so that makes this debatable from 62-66, as the greatest 5 years in MLB history.
Now its up to the individual. Both great.
Edit: Now if you include the DH, Mound Height, Strike Zone, and Pitching in the NL. Forgot Fenway and Dodger Stadium.
I'll go with Pedro.