The Four Factors you see for each game represent each team's raw performance thus far in four important categories (pass and rush efficiency, pass and rush efficiency against) relative to league average (where 100 is league average and anything above is good).
Along with the Four Factors, you'll see two other numbers: Generic Win Probability (GWP) and Game Probability (PROB). The GWP is the probability a team would beat the league average team at a neutral site. It can be found for all teams here. The PROB is each respective team's chance of winning this particular contest. Your host, Brian Burke, provides PROBs to the New York Times each week, and those numbers (along with methodology) can be found here.
Finally, a glossary of all unfamiliar terms can be found here.
New York Giants at Minnesota | Sunday, December 12 | 1:00pm ET
• True Fact: Americans are holding their collective breaths, waiting to find out whether Brett Favre or Tarvaris Jackson will start this afternoon's game.
• Other True Fact: Americans should probably stop holding their breaths, lest they suffer some sort of oxygen deprivation-related brain damage.
• As for which is the better option -- Favre or Jackson -- our host Brian Burke suggests the latter might have an edge on the former, although it's not entirely clear.
• A notable thing is that, despite what must be considered a disappointing season on the face of it, the Vikings are actually ranked tenth per GWP, with a 0.59 mark.
• They're also the NFL's fifth-unluckiest team (as you can see below in the GWP Luck table).
Kansas City at San Diego | Sunday, December 12 | 4:15pm ET
• Per the NFL maps at The 506, this game (a) will have relatively limited broadcast reach and (b) is being called by Gus Johnson.
• True Fact: Gus Johnson is America's ambassador to Joy.
• Debatable Opinion: Gus Johnson ought to be the No. 1 NFL broadcaster for CBS.
• Regardless of my thoughts of the matter, perhaps consider Noel Murray's thoughtful answer to the question "Why does most modern sports broadcasting suck so hard?" -- available at The Onion's AV Club.
• Oh, also maybe consider how San Diego -- i.e. the best football team -- might not actually make the playoffs.
New England at Chicago | Sunday, December 12 | 4:15pm ET
• The most representative image of the 2010 Patriots is the shining, golden visage of quarterback Tom Brady.
• Either that, or the grim, unsmiling face of coach Bill Belichick.
• For Chicago, it's probably Julius Peppers and/or Israel Idonije -- both among the top-five defensive ends in +WPA and +EPA -- about to assassinate an opposing player.
• Or Jay Cutler, himself, being assassinated.
• Yes, this is what passes for football analysis these days.
GWP Wins and Luck
Here's the table, through Week Thirteen and sans comment, of GWP wins and losses as compared to actual wins and losses.