Top 20 fWAR 2014-2018 pitchers
1. Clayton Kershaw (High School)
2. Corey Kluber (College)
3. Chris Sale (College)
4. Max Scherzer (College)
5. Jacob DeGrom (College)
6. David Price (College)
7. Zack Greinke (High School)
8. Justin Verlander (College)
9. Jake Arrieta (College)
10. Carlos Carrasco (Intl)
11. Stephen Strasburg (College)
12. Jose Quintana (Intl)
13. Gerrit Cole (College)
14. Jon Lester (High School)
15. Chris Archer (High School)
16. Dallas Kuechel (College)
17. Madison Bumgarner (High School)
18. Johnny Cueto (Intl)
19. Cole Hamels (High School)
20. Trevor Bauer (College)
11 of the top 20 here were college players. Of the 6 high schoolers - only Lester and Archer were not drafted in the first round. So there seems to be a slight bias to college success here - much more stark trend at the top of the list. The physical maturity matters. College kids in general are safer, but the upside for college pitchers is still really high, especially compared to say college middle field prospects.