First of all, that was an amazing game, possibly the most entertaining Super Bowl ever. Eli Manning played a great game, but the big story to me is how the Giants defense was able to hold the Patriots to only 14 points.
New York's pass rush obviously had a lot to do with their success. Their secondary played amazingly well too. But one of the biggest factors will probably go unmentioned in all the conventional post-game analysis--the clock.
The research from this article suggested that a heavy underdog could see its chance of winning significantly increase when the number of possessions for each team is reduced. The more possessions for each team, the more likely the better team will eventually come out on top. The fewer the possessions, the more likely that luck or other factors can conspire to create opportunities for the underdog to win. Perhaps the easiest way to think of it is that fewer possessions probably means a lower score, and a single drive or play can cause an upset.
In Super Bowl XLII, each team only had 8 full possessions. (This does not count the Giants 10 sec possession at the end of the 2nd quarter and their 1 sec possession at the end of the game.) Most games feature 10 to 13, the average being 11.5 full drives per game. The Patriot's final possession began with 35 seconds remaining, allowing time for only 3 desperation throws and a sack.
The table below illustrates each team's chance of winning a game with the given number of possessions based on a simulation of each team's historic scoring per possession rates. My original table did not even consider the possibility of 8, but I include it here.
| Possessions |  NE Wins |  NYG Wins | Overtime |
| 8 | 69.8 | 24.1 | 6.1 |
| 9 | 71.4 | 23.5 | 5.1 |
| 10 | 72.7 | 22.4 | 4.9 |
| 11 | 74.0 | 21.5 | 4.5 |
| 12 | 75.5 | 20.7 | 3.8 |
| 13 | 76.5 | 20.0 | 3.5 |
How did the game yield so few possessions? Long drives with high 3rd down conversion percentages appears to be the biggest reason. The Giants started the game with an amazingly long 10 minute drive culminating in a field goal. The Patriots didn't even finish their first drive until the second quarter. The Patriots started the third quarter with a drive of over 8 minutes resulting in a turnover on downs.
If each team had 2 or 3 more possessions, New England may well have been able to overcome their 3-point deficit. It's hard to say that with any certainty because the Giants slightly outplayed the Patriots almost all night. Congratulations to the Giants and their fans.
I would have loved to see Rupert Murdoch's face toward the end of the opening drive. He was probably on the phone with Goddel screaming "I need a TV timeout! I don't care How you do it! Get the referees to make a measurement or something! These ads pay 2.7 million!!"
Good point about the shortened game. Ultimately, this was not a predictable event. You couldn't project the Giants defensive line playing the game of their collective lives, and the Patriots' fantastic offensive line playing, by far, their worst game of the year. Even with all that, it took the remarkably unlikely Tyree grab to give the Giants a chance to win.
I think you're completely right about the importance to the Giants' winning of reducing the number of possessions in this game, and about why, but I think there might be some more to the concept.
When you write, "The more possessions each team has, the more likely it is the better team is going to eventually come out on top." the assumption seems to be that the "better team" is the better offensive team, for whom this is certainly true. But there are other cases. The golden stat for possessions is points-per-possession. Higher PPP = victory, absent some sort of fluke on a "non-possession" play. But net PPP is the result of both offense and defense.
Imagine a team with only an average offense, or a sub-average offense, but a superior defense. It's a good team, better than most, maybe very good, but it isn't going to benefit any on average by getting its offense a lot of possessions. Its comparative advantage that produces its net +PPP is its defense.
And remember the human element of football defense. Defenders have to cover the entire field every play while the offense knows just where it is attacking. Defenders have to hide their schemes, while the offense given time can ferret them out. Defenders are much more subject than attackers to exhaustion and exposure if they are on the field a long time. (Think of why Buddy Ryan punched out Kevin Gilbride when the latter's run-and-shoot offense was producing 65-second three-and-outs.)
If expected net PPP is constant, then mathematically a higher number of possessions helps the "better" team, always. But if a team's advantage is defensive, it gets its net +PPP from its defense, then a lot of plays and possessions that leave its defense on the field subject to exhaustion and exposure may reduce its expected net PPP during the course of the game, and reduce its winning percentage. A team with an average game score of 20-10 has a higher expected winning percentage than one with an average score of 30-20.
If all this is true, then when a superior offensive team plays a superior defensive team, when the latter chews up the clock to reduce the number of possessions and plays, it's not just hoping to improve its odds of somehow getting lucky, it's actually playing aggressively to its strength. It also means that when great defensive-oriented teams like Lombardi's Packers, Shula's Fish, and Noll's Steelers ran over average teams all season long with extremely run-oriented offenses that consumed the clock and reduced possessions, they weren't inadvertently increasing their own risk of being upset, they were aggressively maximizing their net +PPP and winning expectations.
As to the Giants last Sunday, they were so different during their last five games compared to the rest of the season I don't know if they were an offensive team, defensive team, or what ;-) . Surely they wanted to reduce Brady's possessions because the Pats were the better offensive team. But if they were basing their fight on their D-line, then reducing the number of plays wasn't just hoping for luck, it was also maxing their strength. And that 10-minute opening drive was just what the doctor ordered for both objectives. Sort of Gilbride's Revenge on Buddy!
That post makes no sense^
There is no such thing as a defensive or offensive advantage for points per possession. You just take the expected PPP scored and subtract the expected PPP allowed. Say you have a great defense but a bad offense. You might score 1.7 PPP and allow 1.5. Subtract that, and for every possession on the field, you gain .2 points (expected).
Now reverse it, say you have a great offense and bad D, you score 2.5 PPP and allow 2.3 PPP. Subtract them, and same thing, you gain .2 points for every possession you are on the field. Offensive/defensive strengths don't affect it.
In terms of the argument for good defenses being more likely to get tired, that would take an ambitious statistical study to prove. Common sense says a bad defense is just as likely to get tired as a good one, so shortening the game for a good defense doesn't help much at all.
Yes, points per possession is more important than points per game.
But the idea that the worst team wants fewer possessions isn't based on just offense.
If team A is good enough to "on average" outscore team B 3:2, it's to team B's advantage to keep the game to the number of possessions such that the score is at most 24-16 late, rather than having it be 30-20 late, for example.
Another way of thinking about it is the Law of Large Numbers. The more data you have, the more likely it will be to follow the expected trends. Rolling, say, 10 dice and averaging 2.0 or 5.0 instead of 3.5 is more likely than rolling > 10 dice and averaging 1.5 off the expected mean.