If you look at bbref’s similarity scores, here are Heyward’s top ten comps at age 20:
1. Jackson Chourio - still only 21
2. Willie Mays (156.2 WAR)
3. Sam Crawford (74.9)
4. Ken Griffey, Jr. (83.8)
5. Cesar Cedeno (53.1)
6. Bryce Harper (54 and counting)
7. Manny Machado (62.3 and counting)
8...