How Upsets Were Determined
First, the power rankings for each team was determined, using the
  first 16 weeks of play (the final week of games is left out to avoid
  skewing the data with the results of games where teams are resting
  their starters, or otherwise not trying).
However, unlike the weekly power rankings, which give more weight
  to recent games than ones earlier in the season, the power rankings
  for the season upsets are unweighted—all game results count
  equally.  This means that the matchup ratio values (ρ) below
  will not correspond to the matchup ratios given in the respective
  game pick posts.
Once the power rankings are computed, every game of the season is
  picked using those rankings.  The wrong picks are then sorted by
  matchup ratio, with the games featuring the largest ratios featured
  below.
Any game that is not a "real" upset (because a team is resting its
  starters, or is indirectly affected by such) is removed from the
  list.
Dishonorable Mention: some games that missed the top-10 cut
Week 14: The Jets defense held the Dolphins to just 10 points, but
  that wasn't enough for their offense that only managed 6.
Week 3: Janikowski misses 3 field goals, and the resurgent Raiders
  can't get past the struggling Cardinals.
Week 16: The Cowboys spot the Cardinals 21 points, and can't recover.
Week 4: Chris Johnson has a bad day, and Titans' turnovers give
  the Broncos enough for a win.
Week 4: The Redskins knock Michael Vick out of the game, and Kevin
  Kolb can't produce enough offense for the Eagles to pull out a win.
The Top 10 Upsets of the 2010 Season
- Week 7: Redskins 17, Bears 14 (ρ=1.1471)
  The Bears' offense had probably their worst game of the season,
  generating 7 punts, 6 turnovers, and 4 sacks.  This game was only
  close because McNabb threw a couple interceptions.
 
- Week 6: Dolphins 23, Packers 20 (OT) (ρ=1.1475)
 The
  The Packers have had one of the best defenses in the league this
  year, giving up the fewest points of any team except the Steelers.
  But in this game, the Packers' run defense struggled, which let the
  Dolphins control the ball and keep it away from the Packers'
  struggling offense.
 
- Week 14: Packers 3, Lions 7 (ρ=1.1595)
  Easily the most egregious example of the Packers' struggling
  offense.  This game cost them a chance to win their division, and
  isn't ranked higher on this list only because the Lions finished the
  season on a 4-game winning streak.
 
- Week 3: Chargers 20, Seahawks 27 (ρ=1.1717)
  How do you generate more than 500 yards of offense and yet only have
  20 points on the scoreboard?  Three lost fumbles, two interceptions,
  and a failed 4th-down conversion are a good start.  The Chargers'
  special teams took a big chunk of the blame for this loss, but
  that's a whole lot of offensive futility for a team that was
  supposed to win their division.
 
- Week 10: Chiefs 29, Broncos 49 (ρ=1.1973)
  Part of the Chiefs resurgence this year has been a good, or at least
  adequate defense.  They are 9-1 when they hold their opponent to 20
  or fewer points.  But the Chiefs also had a couple of defensive
  breakdowns this season, and this was the biggest, giving up 7
  touchdowns to the Broncos offense that only made it past 28 points
  three times all season.
 
- Week 2: Ravens 10, Bengals 15 (ρ=1.2160)
  Back in week 2, this didn't seem like that much of an
  upset—the Bengals were the defending AFC North champions, they
  were supposed to win games like this.  But in hindsight, it
  should've been a red flag that the Bengals could only score 15
  points in spite of intercepting Joe Flacco 4 times.
 
- Week 5: Packers 13, Redskins 16 (OT) (ρ=1.2170)
  More offensive struggles for the Packers, and again the Redskins
  manage to catch their opponent having one of their worst games of
  the season.
 
- Week 9: Patriots 14, Browns 34 (ρ=1.2349)
 Perhaps
  the Patriots were looking ahead to the game at the Steelers that
  followed this one.  But somehow the Browns (and particularly Peyton
  Hillis) were the only team this season that was really able to
  expose the Patriots unimpressive defense this season.
 
- Week 6: Seahawks 23, Bears 20 (ρ=1.2566)
 Unlike
  Week 7's Redskins @ Bears game, the Bears didn't have any turnovers
  in this game.  But Cutler was sacked 6 times (including once for a
  safety), and the offense could only sustain four drives, and going
  3-4 on field goal tries.  The Seahawks only had three sustained
  drives, but they all finished with a touchdown, and that was enough
  to put them by the struggling Bears.
 
- Week 5: Saints 20, Cardinals 30 (ρ=1.2708)
 The
  Saints had three turnovers in this game, and the Cardinals turned
  them all into touchdowns.  As the Cowboys found out on Christmas,
  even the Cardinals can get a win when you spot them 21 easy points.
 
Eliminated Games
This season, the only eliminated game was the Cowboys week 17
  defeat of the Eagles, which would have otherwise appeared in the
  "Dishonorable Mention" section.
Biggest Upsets According to the Line
| Week | Game | Line
 | 
|---|
| 10   | Cowboys
    33, Giants 20 | Giants -14
 | 
| 16   | Vikings
    24, Eagles 14 | Eagles -14
 | 
|  7   | Browns 30,
  Saints 17 | Saints -13½
 | 
| 13   | Raiders
    28, Chargers 13 |  Chargers -13
 | 
| 17   | Buccaneers
    23, Saints 13 | Saints -9
 | 
|  2   | Bears 27,
  Cowboys 20 | Cowboys -8½
 | 
|  4   | Colts
  28, Jaguars 31 | Colts -8½
 | 
|  6   | Chargers
  17, Rams 20 | Chargers -8½
 | 
| 16   | Chargers
  20, Bengals 34 | Chargers -7½
 |