There is a sequence of events that have been discussed on HH that have not quite been framed as follows:
1) First players get scouted by independent professional scouts as well as teams personnel scouting staffs.

2) Secondly, the NFL draft occurs and risks are taken effecting future success.

3) The rookies then play in a seasons games if they have demonstrated sufficient talent. 

Other things effect these rookies playing time, i.e., experienced players at the same positions.  I am posting information on the 2009 first round draft picks in these 3 categories just to see how it plays out.  It may be more significant to see have these draft picks do in their 2nd season.  The 2008 draft picks can have similar information.

2009 Draft - http://www.nfl.com/draft/2009
Draft Tracker - Round One order
1    Lions        Matthew Stafford,  QB,  Scouts Inc grade:96 - Adj. PFF score:74 - Ov Rank: 7
2    Rams        Jason Smith,          OT,  Scouts Inc grade:97 - Adj. PFF score:96 - Ov Rank:2
3    Chiefs        Tyson Jackson,         DE,   Scouts Inc grade: 94 - Adj. PFF score:12 - Ov Rank:14
4    Seahawks   Aaron Curry         OLB Scouts Inc grade:97 - Adj. PFF scor:75 - Ov Rank:1
5    Jets        Mark Sanchez         QB   Scouts Inc grade:95 - Adj. PFF score:98 - Ov Rank: 8
6    Bengals        Andre Smith         OT Scouts Inc grade:95 - Adj. PFF score:97 - Ov Rank:10
7    Raiders        Darrius Heyward-Bey,WR, Scouts Inc grade:90 - Adj. PFF score:70 - Ov Rank:25
8    Jaguars        Eugene Monroe,    OT, Scouts Inc grade:96 - Adj. PFF score:80 - Ov Rank:5
9    Packers        B.J. Raji,         DT, Scouts Inc grade:96 - Adj. PFF score:89 - Ov Rank: 4
10    49ers        Michael Crabtree,  WR, Scouts Inc grade:96- Adj. PFF score:100 - Ov Rank:3
11    Bills        Aaron Maybin,         DE, Scouts Inc grade:96 - Adj. PFF score:77 - Ov Rank:6
12    Broncos        Knowshon Moreno,RB, Scouts Inc grade:94 - Adj. PFF score:101- Ov Rank:12
13    Redskins    Brian Orakpo,          DE, Scouts Inc grade:95 - Adj. PFF score:101- Ov Rank:9
14    Saints         Malcolm Jenkins,  CB, Scouts Inc grade:94 - Adj. PFF score:87 - Ov Rank:13
15    Texans         Brian Cushing, OLB, Scouts Inc grade:92 - Adj. PFF score:131- Ov Rank:19
16    Chargers     Larry English,         DE, Scouts Inc grade:89 - Adj. PFF score:60 - Ov Rank:28
17    Buccaneers Josh Freeman,         QB, Scouts Inc grade:85 - Adj. PFF score:94 - Ov Rank:46
18    Broncos         Robert Ayers,        LB, Scouts Inc grade:93 - Adj. PFF score:103 - Ov Rank:15
19    Eagles       Jeremy Maclin,        WR, Scouts Inc grade:95 - Adj. PFF score:100 - Ov Rank:11
20    Lions     Brandon Pettigrew,   TE, Scouts Inc grade:93 - Adj. PFF score:86 - Ov Rank:17
21    Browns      Alex Mack,        C, Scouts Inc grade:87 - Adj. PFF score:133 - Ov Rank:39
22    Vikings      Percy Harvin,        WR, Scouts Inc grade:89 - Adj. PFF score:115 - Ov Rank:27
23    Ravens      Michael Oher,        OT, Scouts Inc grade:92 - Adj. PFF score:109 - Ov Rank:20
24    Falcons      Peria Jerry,        DT, Scouts Inc grade:91 - Adj. PFF score:95 - Ov Rank:23
25    Dolphins  Vontae Davis,       CB, Scouts Inc grade:90 - Adj. PFF score:104 - Ov Rank:26
26    Packers      Clay Matthews,      OLB, Scouts Inc grade:91 - Adj. PFF score:140 - Ov Rank:21
27    Colts      Donald Brown,      RB, Scouts Inc grade:89 - Adj. PFF score:100 - Ov Rank:30
28    Bills      Eric Wood,      C, Scouts Inc grade:86 - Adj. PFF score:85 - Ov Rank:41
29    Giants      Hakeem Nicks,      WR, Scouts Inc grade:91 - Adj. PFF score:110 - Ov Rank:22
30    Titans      Kenny Britt,      WR, Scouts Inc grade:88 - Adj. PFF score:106 - Ov Rank:34
31    Cardinals Chris Wells,      RB, Scouts Inc grade:93 - Adj. PFF score:106- Ov Rank:16
32    Steelers     Evander Hood,      DT, Scouts Inc grade:86 - Adj. PFF score:102- Ov Rank:42
             (Ziggy)

2009 ESPN projected overall rank = Ov Rank
Adj. PFF score = (2009 Pro Football Focus overall rating x 2) +100