QBR ranks: 49ers' Alex Smith wins ugly

The San Francisco 49ers did not need their best offensive performance, or anything approximating it, to defeat the Detroit Lions in Week 6.

They needed strong defense and special teams, plus a clutch scoring pass from Alex Smith to Delanie Walker, for their first 5-1 record since 1998.

Smith's 6-yard touchdown toss in the final two minutes staked the 49ers to a 25-19 victory at Ford Field. That was what mattered Sunday, one reason I wouldn't read too much into the season-low 10.6 Total QBR for Smith in this game.

Yes, Smith completed only 6 of 17 passes for 48 yards in the second half. Yes, Smith tossed a killer interception in the third quarter, setting up the Lions' go-ahead touchdown. Yes, only two of his nine third-down passes produced conversions. Yes, 16 of the 19 second-half plays featuring Smith as a runner or passer lowered the 49ers' win probability, according to Albert Larcada of ESPN's analytics team.

Winning ugly beats losing pretty any day. The way Smith responded to that third-quarter interception allowed him to leave the field victorious for the eighth time in his past 11 regular-season starts.

The season-low 10.6 figure from Smith came one week after he set the QBR standard for NFL quarterbacks this season, posting a 98.2 out of 100 during a 48-3 victory against Tampa Bay.

Quick thoughts on how NFC West passers graded out as they did by Total QBR in Week 6, with NFL passer ratings in parenthesis as a reference point:

  • Alex Smith, 49ers (10.6 QBR, 60.0 NFL rating): Smith completed 17 of 32 passes for 125 yards with one touchdown, one interception, one lost fumble and two sacks. He averaged 3.9 yards per attempt, his lowest average in a regular-season game since Week 9 of the 2007 season. The 49ers converted just twice in 14 third-down tries. This was a rough performance, no question, but also one the 49ers could live with given the outcome.

  • Sam Bradford (20.2 QBR, 76.0 NFL rating): Bradford completed 28 of 44 passes for 321 yards with no touchdowns, one interception and one fumble, recovered by the Rams. The interception Bradford threw in the end zone was costly. His longest completion, a 45-yarder to rookie tight end Lance Kendricks, featured considerable yards after the catch. QBR gives more credit to receivers than to quarterbacks for yards after the catch. That was appropriate here. The stiff-arm Kendricks delivered against Green Bay safety Morgan Burnett was key to helping him spring the long gain.

The chart shows how quarterbacks from games involving NFC West teams fared in Total QBR for Week 6. The Packers' Aaron Rodgers was the only one performing at a high level. Fifty represents an average performance.

2011 Relevant NFC West QBR Ranks: Week 6