My passing offense metric, updated with last week's results.  See below an explanation of the statistical details:  It's the same text I've posted in previous weeks.  The only difference is this diary gives the values of all QBs who threw at least one pass this season, organized into three groups, based on the number of attempts:

• Those with at least 160 attempts;
• Those with less than 160, but at least 30 attempts; and
• Those with less than 30 attempts.

As I predicted, Romo fell short of his value of last season, but nonetheless had a very strong year.  That he is a franchise-caliber NFL quarterback should be plainly obvious now to all but the most inveterate Cowboys haters.  I'll have to do more digging into my database, but I believe the most similar quarterbacks to Romo bounced back with a better season at the age of 28, overcoming this strange slump that affects 27-year olds.

And check out Brad Johnson.  Despite all the angst about his age, his limited appearance against Washington didn't turn out bad at all.

Other notes:

• The league average value this season for quarterbacks was 0.370, the highest value since 2004.  The league-wide benefits of passing have been rising for two straight years.
• Tom Brady's season was the second greatest ever in my database, and was easily the highest value of his career.
• Brett Favre narrowly missed setting the highest value of his career, which was set in his MVP season of 1995 with a 0.527 value.  His value for this season was 0.526.
• Similarly, Jeff Garcia has had several excellent seasons in his career, but now at the age of 37, he had his best season ever.
• Does anyone now doubt Jack del Rio's decision to dump Byron Leftwich and hand the ball to David Garrard?  He had played well before this season, but this year he was fantastic, and is a big reason why no one wants to play Jacksonville in the playoffs.
• Peyton Manning had the lowest value since 2002, although all the injuries faced by the Colts certainly was a major contributor.
• Reports of Donvan McNabb's demise appear to be greatly exaggerated.  Despite looking shaky early and dealing with an offensive line that was at times porous, he turned in the third highest value of his career.
• On the other hand, Eli Manning's career is in a tailspin.  After improving to a respectable 0.39 in 2005, he declined to 0.31 last year, and this year sunk to a level that approaches a replacement level quarterback.
• Jason Campbell declined slightly from his solid season last year, but I would not write him off just yet.  He's still young, and I expect good things from him in the future.
• Phillip Rivers also declined, from his excellent season last year.  In the long run, I still think the Chargers made the right decision in letting Brees go, but in any event it will be fun to watch how things play out for these two QBs over the next several years.
• Ben Roethlisberger bounced back nicely from his nighmarish 2006 season.  It wasn't at the same level as his fantastic 2005 value, but was plenty good, and bodes well for the Steelers' future.
• For those who recall his value early in the year, Drew Brees made a remarkable comeback, nearly finishing in the top ten.  His career has been strangely predictable, alternating good years with no-so-good years, and this was the down year in the cycle.  I fully expect him to bounce back with a strong season next year.
• Respect is due for Kurt Warner.  It looked like he was totally washed up after the 2003 season, but since he's left the Rams, he's turned in four straight above-average seasons.  Now that Garrard is a starter at Jacksonville, I think he is the best backup QB in the league.

Here's the intro I've posted on previous weeks:

I've been using a passing offense metric for many years now to gauge how well a QB is doing.  Inspired by baseball SABRmetrician Bill James, I performed linear regressions of NFL statistics and concluded from a big picture point of view, only two statistics mattered:  Yards gained from scrimmage, and turnovers.  The best fit to matching points scored came when assuming the following coefficients:

Ten yards gained from scrimmage = +1.0 points; and
One turnover lost = -6.0 points.

Simply put, teams that score points rack up yardage and don't commit turnovers.  Note how powerful turnovers are:  A team can, for example, gain 55 yards of offense, but if they turn it over the next play, they actually ended up hurting their team.

With that in mind, I created the points per pass metric, which calculates the effectiveness of quarterbacks.  The above two coefficients are used to determine, on average, how many points a quarterback (and his offensive teammates, since everyone else contributes to his success or failure) creates with each passing attempt.  It takes the simple yards per attempt metric we're all familiar with, adjusts it for sacks, and further adjusts it for turnovers.  One interception equates to minus six points; one fumble equates to minus three points.  I treat fumbles as half a turnover, since there's essentially a 50/50 chance of recovering or losing a fumble.  The results will probably be unsurprising for the most part, but sometimes they can appear odd.  One of the things that may cause these oddities are fumbles.  Most people, when looking over a QB's stat line, don't think about fumbles; they just look at yardage, attempts, touchdowns, interceptions, and maybe sacks.  But fumbles are very important, since they are essentially half a turnover.

Quarterbacks with at least 160 attempts:
Brady, NE                                        0.67
Garrard, Jax                                    0.62
Garcia, TB                                        0.57
Manning, Ind                                  0.54
Favre, GB                                        0.53
Romo, Dal                                       0.48
Hasselbeck, Sea                             0.47
McNabb, Phi                                    0.47
Palmer, Cin                                     0.45
Schaub, Hou                                   0.45
Brees, NO                                       0.44
Anderson, Cle                                 0.44
Cutler, Den                                     0.44
Roethlisberger, Pit                          0.42
Harrington, Atl                                0.41
Warner, Ari                                     0.40
Rivers, SD                                       0.36
Campbell, Was                               0.35
Kitna, Det                                       0.34
Edwards, Buf                                  0.33
Rosenfels, Hou                               0.32
Pennington, NYJ                              0.31
Losman, Buf                                   0.31
Lemon, Mia                                     0.31
Jackson, Min                                   0.31
Culpepper, Oak                              0.30
Huard, KC                                       0.30
Griese, Chi                                      0.28
Boller, Bal                                       0.28
Manning, NYG                                 0.28
Croyle, KC                                       0.27
Young, Ten                                     0.26
McNair, Bal                                      0.25
Testaverde, Car                              0.25
Bulger, StL                                      0.25
Grossman, Chi                                0.25
Clements, NYJ                                 0.24
Smith, SF                                        0.18
Frerotte, StL                                   0.08
McCown, Oak                                 0.03
Dilfer, SF                                         0.01

Quarterbacks with between 159 and 30 attempts:
Collins, Was                                   0.64
Delhomme, Car                              0.54
Collins, Ten                                    0.53
Bollinger, Min                                 0.46
Redman, Atl                                   0.42
Smith, Bal                                      0.42
McCown, TB                                   0.41
Hill, SF                                           0.38
Gray, Jax                                       0.36
Holcomb, Min                                 0.36
Orton, Chi                                     0.35
Leinart, Ari                                    0.33
Sorgi, Ind                                      0.31
Green, Mia                                    0.31
Moore, Car                                    0.28
Ramsey, Den                                 0.25
Carr, Car                                       0.16
Feeley, Phi                                    0.15
Batch, Pit                                      0.14
Beck, Mia                                      0.09
Russell, Oak                                -0.04
Leftwich, Jax                               -0.09

Quarterbacks with less than 30 attempts:
Gutierrez, NE                               1.50
Rogers, GB                                   0.63
Johnson, Dal                                0.58
Quinn, Cle                                    0.56
Walter, Oak                                 0.48
Wallace, Sea                                0.36
Weinke, SF                                   0.27
Lorenzen, NYG                             0.26
Gradkowski, TB                            0.22
Wright, NYG                                  0.17
Berlin, StL                                    0.12
Nall, GB                                        0.11
O'Sullivan, Det                            -0.19
Rattay, Ari                                  -0.28
Frye, Cle                                     -0.38
Thigpen, KC                                -0.40
Cassel, NE                                  -0.74
Volek, SD                                    -0.76