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On November 15th, 2009, in front of the entire country on Sunday Night Football, Bill Belichick did the unthinkable when he attempted fourth down conversion from his own 28-yard-line late in a matchup against the rival Colts.

A short pass to the always-reliable Kevin Faulk was bobbled just enough to fail the conversion. The Colts took over inside the 30, and it was not soon after until Peyton Manning delivered the game-winning touchdown pass to Reggie Wayne.

The infamous “4th-and-2” decision ignited the sports radio waves for weeks, with Belichick drawing plenty of criticism for daring to go against the accepted norm. After all, one can assume that Belichick sent a bad message to his defense by not punting in what looked like an obvious punting situation. Putting the ball in the hands of one of the greatest quarterbacks of all time, in Peyton Manning, is just asking to lose.

Even Rodney Harrison, who played for Belichick, called it the “worst decision I’ve ever seen Bill Belichick make.”

Or was it?

Taking a look beyond the predictable storylines, Belichick may have had more logic to his fateful decision than had he punted, like “normal” coaches (with a lot less job security) would have done.

Further analysis done at AdvancedNFLStats.com suggests that Belichick actually gave his team the best chance to win:

A punt from the 28 typically nets 38 yards, starting the Colts at their own 34. Teams historically get the TD 30% of the time in that situation. So the punt gives the Pats about a 0.70 [winning percentage].

Statistically, the better decision would be to go for it, and by a good amount.

So, did Belichick make the all-time blunder that everyone assumed at first, or could he have been on to something after all?

The Odds

A simple way to look at fourth downs is basic success rate. According to AdvancedNFLStats.com, from 2002-2008, teams generally hovered around the 50/50 mark when going for it on fourth down:

Year 4th Downs Conv. Attmpts Rate (%) Conversions Success (%) 2002 4205 497 12 252 51 2003 4305 501 12 232 46 2004 4185 454 11 219 48 2005 4248 465 11 223 48 2006 4218 473 11 239 51 2007 4152 533 13 261 49 2008 4096 468 17 252 54

As a result, coaches viewed a fourth down attempt as a coin flip at best, and the idea of kicking (either a punt or a field goal) went largely unchallenged—that is, until Cal-Berkeley professor David Roemer challenged the long-standing tradition in 2005.

Because of the relatively small sample size of fourth down attempts, Roemer based his analysis on the success on third downs, which makes sense—teams treat third downs in the same do-or-die manner as they would fourth down, with few exceptions in late-game situations.

With the use of his formulas, here is what Roemer found:

A team facing fourth-and-goal within five yards of the end zone is better off, on average, trying for a touchdown. At midfield, on average, there is an argument to go for any fourth down within five yards of a first down. Even on its own 10-yard-line -- 90 yards from the end zone -- a team within three yards of a first down is marginally better off, on average, going for it.

Brian Burke of AdvancedFootballStats.com has developed his own method of optimizing fourth down attempts.

Burke’s theory involves a metric he calls “expected points”, which varies based on field position. Predictably, a team’s expected points are much higher starting closer to the opponents end zone, and lower when backed-up in their own end.

In fact, expected points go into the negative when starting inside the 10, meaning the opposing team has a better chance of scoring than they do on their next possession.

With this formula, Burke has made a calculator that will determine whether or not a fourth down attempt is warranted, based on the score, time remaining, field position and the yards needed to gain.

I calculated what would normally be a punting situation: It's 4th-and-5, with six minutes left in the third quarter, down seven points on my own 45 yard line.

What should I do?

Stat Go For It Punt FG Attempt Success Rate: 0.49 - 0 WP Success 0.3 0.23 0.31 WP Fail: 0.18 - 0.17 WP Total: 0.24 0.23 0.17 Break-Even: 0.42

Go for it.

According to Burke, I actually have a (slightly) higher chance of winning (noted by the winning percentage differential) if I attempt the conversion, even with a full quarter of football left to play.

What’s the Hold Up?

As convincing as these statistics may seem in a vacuum, the reality is that coaches are dealing in a completely different realm that is filled with flawed human beings with incalculable emotions that are impossible to quantify with mere numbers.

For instance, while going for it on 4th-and-1 may seem like a logical choice after delving into quantitative analysis, when your running back is injured or you are facing a defensive line that has dominated the game, sending out the goalline offense is a much more intimidating proposition.

These stats don’t take into account the hundreds of things that can go wrong on any given play. Whether it is a bad snap, a lineman tipping off the running lane, a false start or a missed assignment, there are too many factors that go into such a high-stakes play to possibly quantify on a computer.

On these plays, nerves are high, hands get tight, feet get heavy and minds speed up. A routine block or catch suddenly carries immeasurable weight.

It is for this reason why Super Bowl-winning head coaches balked at the idea of going for it more often, despite the overwhelming statistical evidence that backs it up.

Reacting to Roemer's analysis, Bill Belichick and Mike Sherman share concerns about the repercussions of a failed conversion that go beyond a simple percentage:

"Do we punt and use our timeouts?" Belichick asked. "Do we have confidence in our field-goal kicker? Are they going to blitz or not? "If I don't get the first down, what are the repercussions?" asked Packers head coach Mike Sherman. "Are they moving the football? If you're on the road and don't get that fourth down the momentum is going to change over to the other team."

More importantly, Bill Cower points out how many people are counting on you to make the sensible decision:

"It's easy to sit there and apply a formula, but it's not always the easiest thing to do on a Sunday. There's so much more involved with the game than just sitting there, looking at the numbers and saying, 'OK, these are my percentages, then I'm going to do it this way,' because that one time it doesn't work could cost your team a football game, and that's the thing a head coach has to live with, not the professor."

Even if going for it is the better statistical decision, the game of football, unlike blackjack, has results that are altered by emotion. If a coach makes an outlandish decision to go for it and fails, the resulting firestorm can have a negative long-term impact on the team that can develop into a distraction— just like the one Bill Belichick had to deal with after his infamous 4th-and-5.

So, What Should Head Coaches Do?

As difficult as it may be for even the most old-fashioned coaches, ignoring this relatively new evidence of fourth-down success may have cost their teams many wins without even knowing it.

The truth is, teams are too hesitant when it comes to keeping the offense on the field on fourth downs. Coaches, by nature, are paranoid creatures that want to leave as little to chance as possible.

John Fox was paranoid enough to take the ball out of Peyton Manning's hands in the 2012 AFC playoffs, which may have cost him the game.

Yes, the ramifications for missing an attempt can extend beyond the field. But if it prevents your team from losing, wouldn't all of that “lost momentum” be thrown out the window?

Coaches do have a valid argument when it comes to all of the in-game factors that go into such an important decision that cannot be quantified by numbers. If a coach has no confidence in his team’s ability to get one yard against the opposing defense, why should he trot his offense back onto the field?

Four years removed from Roemer's study, it is possible that Belichick did take the analysis seriously, leading to the infamous 4th-and-2 play.

As annoying as it must have been to answer relentless questions from fans and media about his bold decision, Belichick and his team have gone on to great success since then, reaching a Super Bowl in the process.

However, not many coaches have the platform that Belichick does to make such a decision and get away with failure. With unlimited job security, Belichick can experiment with ideas that other coaches simply cannot get away with, unless they have rousing success.

It is easy to make these decisions behind a computer screen, but when you're on the sideline and the bullets are flying with your career on the line, doubling-down by sending out the jumbo package on 4th-and-1 isn't as easy as it seems.

Ultimately, coaches should adopt a more aggressive approach in this aspect of decision-making, but it is possible to be too reckless by rolling the dice on every series.