It's funny how the analytics of a sport can often mirror the sport itself. Sabermetrics are as regimented (or more) as the national pastime ever was; basketball analytics have progressed into lively, intersecting data points thanks to new player tracking technology; and heady football talk often enough comes down to whether or not a team or coach should go for it.

Moment-to-moment tactics in a football game are largely inscrutable to most fans, even the most hyper-educated among them. You might notice a defensive line stunting often, or a tight end running delayed routes, but it's usually easier to pick out quality of play (a defensive lineman blowing past the o-line) than it is to see the framework within which this is all happening. The most visible assertions of decision making are the hero calls. Fourth and 2 was Bill Belichick's Little Big Horn; Sean Payton stole the golden fleece out from under Peyton Manning with an onside kick.

In yesterday's game against Denver, San Diego scored with 10:47 left in the fourth quarter to cut Denver's lead to 28-19, before the extra point. CBS's broadcast booth flashed a graphic saying that "The Book" says to go for two in the situation. Phil Simms burst into his nerdstomper dance, and Jim Nantz came along with him. "If that's what the book says, take the book and burn it," Nantz said. No curiosity about why the book might say that, or what the book is actually saying. Just unexamined disdain for numbers that couldn't possibly be right.

The actual math for the situation is hazier than some clear-cut scenarios. With 12 minutes remaining and down nine after the score, the basic calculation suggests you need about a 39 percent chance of converting to make going for two a winning proposition. With 9 minutes remaining, 38 percent. (The original "chart" by Dick Vermeil just says go for 1.) Denver would remain a heavy favorite regardless. If the score had remained a 9-point Denver lead, its Win Probability would have been 90; at 8 points, 88; and at 7, 84.

F0r all normal two-point conversions between 2000 and 2009, the success rate was 47.9 percent—though if play calls were distributed more evenly, the case could be made that that number would float north of 50 percent. Regardless, that's case closed for The Book, right?