QBR ranks: Alex Smith leads NFC West

San Francisco 49ers coach Jim Harbaugh sounded generous when saying quarterback Alex Smith played "exceptionally well" against Seattle in Week 1.

Smith had passed for only 124 yards without a touchdown, after all, and his offense converted just once in 12 third-down chances.

Harbaugh was not alone in his appreciation for Smith. Our weekly QBR rankings placed Smith 10th among 29 quarterbacks in overall performance Sunday, the highest ranking in the NFC West. That comes as a surprise to me given Kevin Kolb's far superior traditional passing stats for Arizona. Kolb passed for 309 yards and two touchdowns.

QBR reflects how passing, rushing, sacks, fumbles and penalties contribute to winning. Any score higher than 50 is above average. Smith, who rushed for a touchdown and suffered no sacks or turnovers, finished with a 66.2 QBR in Week 1. Scores in that range over the course of a season would generally qualify a quarterback for Pro Bowl consideration.

The best single-game totals are often higher, and that was the case during opening week. Buffalo's Ryan Fitzpatrick (91.2) and Green Bay's Aaron Rodgers (91.1) led the NFL in QBR through Week 1 games played Sunday.

The chart below breaks down the various QBR components for NFC West quarterbacks, with "EPA" reflecting expected point added in each category.

Kolb ranks third among NFL players in traditional passer rating at 130.0, but his QBR was only 44.0. Kolb took a 7-yard sack on second-and-20 when the game was tied. He fumbled twice, losing one on a second-and-goal situation. QBR also withholds full credit from quarterbacks for yards gained after the catch, a factor on Kolb's scoring throws to Early Doucet and Jeff King.

Seattle's Tarvaris Jackson ranked last among NFC West quarterbacks thanks largely to the five sacks he took. Pass protection obviously affects sack totals, but QBR assigns quite a bit of blame for them to quarterbacks. Coaches do as well.

2011 NFC West QBR Ranks: Week 1