How well do scouting services predict the NFL Draft?

Two-star J.J. Watt was voted Overachiever of the Year by NFL general managers.

It's always interesting to take a look at which of the recruiting services does the best job of predicting future success.  Just looking at first round picks isn't the most in-depth study, but it's an indicator of accuracy.  The results:

1. Cam Newton: Rivals 5-star, Scout 4-star,
2. Von Miller: Rivals 4-star, Scout 4-star
3. Marcell Dareus: Rivals 3-star, Scout 4-star
4. A.J. Green: Rivals 5-star, Scout 5-star
5. Patrick Peterson: Rivals 5-star, Scout 5-star
6. Julio Jones: Rivals 5-star, Scout 5-star
7. Aldon Smith: Rivals 3-star, Scout 3-star
8. Jake Locker: Rivals 4-star, Scout 4-star
9. Tyron Smith: Rivals 5-star, Scout 5-star
10. Blaine Gabbert: Rivals 5-star, Scout 4-star
11. J.J. Watt: Rivals 2-star, Scout 2-star
12. Christian Ponder: Rivals 3-star, Scout 3-star
13. Nick Fairley: Rivals 3-star, Scout 3-star
14. Robert Quinn: Rivals 4-star, Scout 4-star
15. Mike Pouncey: Rivals 4-star, Scout 4-star
16. Ryan Kerrigan: Rivals 3-star, Scout 3-star
17. Nate Solder: Rivals 3-star, Scout 2-star
18. Corey Liuget: Rivals 4-star, Scout 4-star
19. Prince Amukamara: Rivals 3-star, Scout 3-star
20. Adrian Clayborn: Rivals 4-star, Scout 4-star
21. Phil Taylor: Rivals 4-star, Scout 4-star
22. Anthony Castonzo: Rivals 2-star, Scout 2-star
23. Danny Watkins: Rivals 4-star, Scout 2-star
24. Cameron Jordan: Rivals 3-star, Scout 3-star
25. James Carpenter: Rivals 4-star, Scout 4-star
26. Jonathan Baldwin: Rivals 5-star, Scout 5-star
27. Jimmy Smith: Rivals 3-star, Scout 3-star
28. Mark Ingram: Rivals 4-star, Scout 3-star
29. Gabe Carimi: Rivals 3-star, Scout 3-star
30. Muhammad Wilkerson: Rivals 2-star, Scout 2-star
31. Cameron Heyward: Rivals 4-star, Scout 4-star
32. Derek Sherrod: Rivals 4-star, Scout 4-star

The average star rating for first round picks, as rated by Rivals.com:  3.72

The average star rating for first round picks, as rated by Scout.com: 3.56

Rivals:
5-stars: 7
4-stars: 12
3-stars: 10
2-stars: 3

Scout:
5-stars: 5
4-stars: 13
3-stars: 9
2-stars: 5

You'll notice that each of the 2-stars chosen by the recruiting services plays offensive or defensive line.  This is not a surprise.  As high schoolers fill out and grow, it's very difficult to project how their bodies will mature.  J.J. Watt, a 6'5", 220 lb. high schooler, developed into a 6'6", 292 lb. first round pick.

Smaller players develop sooner physically, so it's somewhat expected that cornerbacks and wide receivers are predicted with more accuracy.  A kid who's faster than everyone at 18 years old will probably still be faster than everyone when he's 21.  Picks #4 through #6 were a wide receiver, a cornerback, and a wide receiver, all three of whom were unanimously chosen as 5-star prospects by the recruiting services.