Trend-spotting: Don't overrate weather

Once again, I'm getting e-mails from readers who want me to quantify the effect of cold weather on performance at this time of the year, something to the effect of: "With the colder weather now upon us, teams obviously will shift their focus to the running game. Because of this, do you think it's wise for me to start (insert name of marginal running back) over (solid wide receiver) in my flex position from here on out."

It makes me want to scream, cry, rant and rave. Heck, if I still had any hair, I'd probably just want to rip that right out too. Let me state this clearly: There's no evidence to support the notion that NFL offenses significantly alter their play calling to favor the running game in cold-weather scenarios.

The decision to remove a more talented player for a lesser one in any week should never be based on the temperature of any game. Don't believe me? Check out the following chart on the right that illustrates the average percentage of NFL rushing yardage to total NFL offense by week over the past nine seasons.

While the final quarter of the season does see some movement to more run-oriented efficiency, the change is not significant by any measure, especially for fantasy footballers. Week 17, which ranks first as the most run-friendly, comes in with 35.8 percent of the total yardage being accumulated on the ground. Week 2, which ranks last, comes in with 31.9 percent of the total yardage via the running game. That movement of 3.9 percent means the difference for the average team in those two weeks is just 12 rushing yards per game. When you allocate that yardage among all of a given team's rushers, including the quarterback, you'll likely come in with another six or seven yards for your back. For leagues that award one point per 10 yards rushing, that means you might go up one point per week.

Is this analysis perfect? Of course it isn't. But a global look like this is accurate enough because at least half of the NFL franchises are in locations that would not be affected by cold temperatures. To further prove the lack of a change, I compiled the statistics for each NFL team and broke the stats into four-week blocks to show there is no significant direct correlation of rushing yardage to colder temperatures and geography. Those results are shown below.

Percentage of Rushing Yardage to Team's Offense

The largest variation versus a team's season average within any four-week period over the second half of the season is owned by the Houston Texans, with plus-5.4 percent during Weeks 13-16. Houston's average daily high temperature in December is about 65 degrees, and the Texans play in a retractable-roof stadium.

The Jacksonville Jaguars posted the second-highest variation at plus-4.7 percent. The daily high temperature in Jacksonville during December is 67 degrees. The Cincinnati Bengals and Denver Broncos also show a measured increase in the last four weeks; however, each team displays similar yardage diversity during one of the four-week segments during the first half of the season. Therefore, there's little reason to believe that the change is temperature-driven.

The increase shown by the Buffalo Bills is driven primarily by two exceptional rushing games in 2004 against the San Francisco 49ers, who finished 2-14 that year, and the Cleveland Browns, who ended the season at 4-12. In those two games, the Bills' ground game racked up 441 yards of rushing, while they passed for only 326 total yards. Such a disparity is a clear statistical anomaly and should be presented as such.

Finally, let me remind you that the New England Patriots have won their last two games at Gillette Stadium that were played in the snow by scores of 59-0 and 47-7. Tom Brady amassed 432 yards and six touchdowns in the former game while Matt Cassel totaled 345 yards and three scores in the latter.

Now, on to the aforementioned abbreviated version of the usual format, which will present just statistics and some minor comments.

On target

Over the past five weeks, here are the NFL leaders in terms of passing targets per game:

Make sure you take note of the appearance of the following players in the above table: Brandon Gibson, Davone Bess, Pierre Garcon, Terrell Owens and Michael Crabtree.

Sizing up the schedule

As the schedule grows shorter, here's a look at the net favorable rushing and passing matchups the rest of the way. A favorable matchup is against a team ranked in the bottom 10 in the league; a nonfavorable features a top-10 team; all other matchups are considered neutral.

Rushing Favorability Rankings

Passing Favorability Rankings

Good luck to all those who survived the regular season and moved into their playoffs.

Ken Daube is a fantasy football analyst for ESPN.com. Feel free to ask him questions via his ESPN.com fan profile, which is available at: myespn.go.com/KenD17.