The mission is clear for the reigning No. 1 team in ESPN's NFL Power Rankings: Keep quarterback Matt Schaub healthy at all costs.
The Texans lost Schaub late last season and had no chance to advance through the playoffs as a result. With Schaub healthy, the Texans stand atop our rankings for a third consecutive week. They're certainly deserving at 10-1.
Despite all this, I broke from the pack in moving San Francisco atop my ballot.
The 49ers have defeated the Chicago Bears and New Orleans Saints by double digits in consecutive weeks. And they've done it with a backup quarterback who might be better than the one they used while posting a 19-5-1 record since 2011. That makes the 49ers what the Saints' Drew Brees called one of the most complete teams -- and a team different from every other contending team in the NFL.
The 49ers play three of their next four on the road, including a date with New England in Week 15. The Texans visit the Patriots in Week 14. The Patriots moved up from eighth to fifth in our rankings this week. They're going to have much to say about how the rankings shake out in the weeks ahead.
And now, a closer look at the rankings heading into Week 13:
Falling (13): Green Bay Packers (-5), Dallas Cowboys (-3), Philadelphia Eagles (-3), Pittsburgh Steelers (-3), Tennessee Titans (-3), Minnesota Vikings (-2), New Orleans Saints (-2), Tampa Bay Bucs (-2), Detroit Lions (-1), New York Jets (-1), Oakland Raiders (-1), San Diego Chargers (-1), Seattle Seahawks (-1).
Rising (10): Cincinnati Bengals (+6), Indianapolis Colts (+5), St. Louis Rams (+5), Cleveland Browns (+3), New England Patriots (+3), Miami Dolphins (+2), Baltimore Ravens (+1), Carolina Panthers (+1), New York Giants (+1), Washington Redskins (+1).
Deadlocked: We broke two ties this week. Atlanta prevailed over San Francisco based on better record, our second tiebreaker. Chicago prevailed over Denver based on previous ranking, our fourth and final tiebreaker. Head-to-head results is the No. 1 tiebreaker. Which team won a game most recently is our third tiebreaker.
Like minds: All five voters ranked the Packers ninth and the Chiefs 32nd. One spot separated high and low votes for the Texans, Falcons, Giants, Colts, Bengals, Dolphins and Cowboys.
Agree to disagree: The Titans and Seahawks generated the largest disparities between highest and lowest votes.
A look at all teams generating high-low gaps of at least six spots in the rankings:
Titans (8): Clayton 22nd, Graziano 30th.
Seahawks (7): Sando 10th, Graziano 17th.
Browns (6): Graziano 23rd, Sando 29th.
Bills (6): Fox 22nd, Graziano 28th.
Steelers (6): Hensley 11th, Fox 17th.
Power Rankings histories: These colorful layered graphs show where each NFL team has ranked every week since the 2002 season.
Ranking the divisions: The NFC North held onto its spot as the highest-ranked division, falling from 10.3 to 12.7 in average ranking. The AFC North and NFC South were next, followed by the NFC West, AFC South, AFC East, NFC East and AFC West.
A voter-by-voter look at changes of at least five spots since last week:
Sando: Steelers (-7), Packers (-6), Titans (-5), Bengals (+5), Giants (+6).
Clayton: Dolphins (+5), Bengals (+6).
Graziano: Packers (-5), Colts (+5), Patriots (+5), Bengals (+7).
Hensley: Packers (-5), Colts (+5), Rams (+6).
Fox: Saints (-6), Bengals (+5), Colts (+5).
For download: An Excel file -- available here -- showing how each voter voted this week and in past weeks.
The file includes a "powerflaws" sheet pointing out potential flaws in voters' thinking by showing how many higher-ranked opponents each team defeated this season.
For example, the Texans outrank the Packers even though Green Bay defeated Houston.
A quick primer on the "powerflaws" sheet:
Column Y features team rankings.
Column Z shows how many times a team has defeated higher-ranked teams.
Change the rankings in Column Y as you see fit.
Re-sort Column Y in ascending order (1 to 32) using the standard Excel pull-down menu atop the column.
The information in Column Z, which reflects potential ranking errors, will change (with the adjusted total highlighted in yellow atop the column).
The lower the figure in that yellow box, the fewer conflicts.