The focus on potential should not entirely overshadow actual in-game performances, of course. With that in mind, and in response to several of your questions, I've acquired from ESPN Stats & Information single-game QBR data for current NFC West passers. Data goes back to 2008, but I singled out 2010 games as most relevant, narrowing the list further by considering only performances in which a quarterback participated in at least 20 action plays.
The chart ranks the 10 best QBR performances last season for games featuring Kolb, Bradford, Alex Smith, Tarvaris Jackson and Charlie Whitehurst. I also included Matt Hasselbeck's games given that Seattle, San Francisco and Arizona considered signing him this offseason.
Whitehurst made only two starts, and neither cracked the top 10.
Jackson, ahead of Whitehurst on the Seattle Seahawks' depth chart, started only one game, for Minnesota. Two of his performances qualified for consideration, and one of them, in relief against Buffalo in Week 13, cracked the top 10.
Jackson tossed two touchdowns with three interceptions in that game. He took only one sack, completed a 31-yard touchdown pass, found Sidney Rice for a 46-yard gain on third-and-11 and scrambled for a 13-yard gain to help set up another score. The Vikings won, 38-14.
I'm still getting a feel for QBR after years of reliance on more basic passing-only stats. As game situations become less critical -- say, early in the game or when the score is lopsided -- QBR gives less weight to specific plays. A quarterback playing well enough to build a big lead won't see his QBR suffer as much if he simply manages the game from that point forward.
In looking at all NFC West performances from last season, I noticed Troy Smith's Week 12 showing during a 27-6 Monday night victory over Arizona rated higher than his rollicking Week 10 showing during an overtime victory against St. Louis.
Smith's pure passing stats against the Cardinals weren't nearly as good as they were against the Rams. His passer rating was 55 points lower against Arizona (61.7) than it was against St. Louis (116.7). But QBR resoundingly favored Smith's Arizona performance, 73.5 to 49.2.
Against Arizona, Smith scrambled for seven yards on third-and-4. He threw a 38-yard touchdown strike to Michael Crabtree in which the ball traveled the full 38 yards in the air, more impressive than if Crabtree had racked up yards after the catch. A 16-yard completion on second-and-10 sustained another scoring drive as the 49ers built a 14-3 lead. Smith's rating peaked during this drive at 97, falling only gradually the rest of the game as the 49ers built a 21-3 lead and coasted to victory.
And now, on with the list. Hasselbeck accounted for four of the 10 highest qualifying QBR performances (there were 50 total). Bradford made the top 10 list three times. Kolb had five qualifying performances and one of them, against Atlanta in Week 6, topped the list.
Hasselbeck also accounted for six of the 18 lowest-qualifying QBR performances. Bradford accounted for five of them.
The five worst overall: Bradford (2.1 QBR) at New Orleans in Week 14; Hasselbeck (2.7) against Atlanta in Week 15; Whitehurst (4.5) against the New York Giants in Week 9; Whitehurst (6.3) against Tampa Bay in Week 16; and Hasselbeck (8.5) against Oakland in Week 8.