Explaining Fourth Down Strategy

After being stoned on third down, the Ravens attempted to pass and gave up a brutal sack to kill a drive that looked promising.

Here's the thing though:  Harbaugh made the right decision and it is really not debatable.

Process not Outcome

Rule number one of understanding in-game decision making is crystal clear:  Decisions must be evaluated based on process not outcome.

What does this mean?  It means we should judge the coach on whether the logic for the decision was correct, given all the available information and evidence at the time, and not based on whether the result itself was the desired one. We cannot use hindsight of the play's result to decide whether it was the right or wrong call.

Why is this important?  It is easy to second-guess a decision when it doesn't work.  Similarly, it's easy to write off a horrendous decision when it does work by mere coincidence. Both happen often in the NFL and usually these decisions are evaluated purely on the result. That is the wrong way to approach it.

Historical data supports decision to go for it in similar situations

We have plenty of data to support Harbaugh's decision.

We'll take two samples of data and examine the conversion rate and calculate how many points a team would expect to get on average, since maximizing points is our clear cut primary goal.

First sample conditions are:

• All games going back to 1998 (the earliest this database goes)
• Games in the 3rd quarter or earlier so we can avoid desperation situations late in the 4th quarter or overtime
• 4th and Goal
• Within 2 yard line

When we run this, we find that teams converted for a touchdown 60% of the time.

0.6* 7 points = 4.2 points.  This means that on average, teams could expect to come away with 4.2 points by going for it in this situation.

Now include the upside of pinning the team inside their 2-yard line if they fail, and the decision is even better given the likelihood of forcing a conservative set of playcalls by the opposing offense and getting the ball back in good field position.

If they kick, the odds of making it are about 100% so 1.0 * 3 = 3 meaning teams can expect to come away with 3 points from kicking it in this situation.  Now include the downside of kicking off and the opponent having the ball at the 20, which affects the overall value of the decision. As you might expect, when a team has the ball at the 2-yard line, it is likely to produce fewer expected points than a team starting at the 20.

What is the breakpoint in which we would not go for it?

If we want to exceed 3 points on average, we can do some simple math to find the bare minimum at which it is a better decision to go for it:  3.01 / 7 points = 0.43.  If teams feel confident in converting 43% of the time or better, they should go for it.

And history shows teams convert 60% of the time.

What about all fourth down opportunities in the Red Zone?

Sample #2 uses the same conditions as sample #1, except now we include all plays within the red zone on 4th-and-2 or less.

Since 1998, there are 648 plays of this type, and they have been converted 62% of the time for a first down or touchdown, which is slightly better as one would expect than the more difficult goal line conversion where the defense can crowd the line of scrimmage.

Arguments for the Field Goal are based on bogus qualitative arguments or benefit of hindsight

The litany of outcries when decisions like these fail are predictable since the game broadcasters are the worst offenders.

Let's take a few of them:

You have to take the points on the road

Doesn't hold up at all.  Why would points on the road be any different than points at home?  If anything, it's the opposite:  you need touchdowns when you get such a golden opportunity to score in order to overcome the disadvantage of playing away from home. Even so, such maxims are impossible to prove and offer little in the way of concrete evidence to take one particular course of action. Your goal is always to score as many points as possible early in the game.

You have to tie the game up there

This definitely has no bearing at all given that this play occurred in the first half with the score just 3-0.  Chasing a particular score that early is meaningless because it is practically guaranteed to not finish at that score  Your only goal that early in the game is to score as many points as humanly possible. The game is not going to remain 3-3 by the end and thus there is literally no advantage for playing for a tie.

You can't give away the momentum

These are professional players who are paid lots of money to devote their lives to this game. To suggest they are frail enough to suffer a dip in play because a good drive ended with a failure at the two-yard line is at best wishful thinking and at worst  completely invented.  It is a purely qualitative statement with little to back it up.

The concept of momentum is a flimsy one at best anyway. Bill Barnwell of Grantland has done several great pieces on the fallacy of momentum. The notion that the game's outcome hinges on the emotional swings of a play in the second quarter doesn't hold up. In truth, believers in football momentum use it anecdotally to fit their particular argument at the time while ignoring the many, many times where it didn't fit at all. Convenient, right?

Think about Super Bowl XLVII for a second. Seemed like a big deal when that 4th-and-9 fake field goal failed didn't it?  How did Baltimore respond to that loss of momentum that many called into question?  They nearly produced a pick six, held San Francisco to a three-and-out, got the ball back at midfield, and then threw a long touchdown pass. So much for the momentum swing there...

Final Thoughts

Fourth down strategy is a much broader topic than I can possibly cover here and other people have done more detailed work on it than I could ever hope to do in my free time. If you are interested, the data is out there in full.

The topic is interesting enough that The New York Times created an automated "4th Down Bot" to analyze every fourth down opportunity live in NFL games and recommend what the coach should do.

The bot liked John Harbaugh's call, too.

The burden is on the players to actually convert it next time.