Every 1st down represents a new set of downs that gives a team a chance another small battle against the defense.

Take the Saints, for example. How many 1st-and-10s (or 1st-and-goals or 1st-and-longer than 10s) have they had this year? By my count, 339. How did I get there? New Orleans has had 105 drives this year (more on that in a moment) and 282 first downs this year. Now remember that in the NFL, a touchdown is also a first down, and the Saints offense has scored 48 touchdowns this year. Therefore, New Orleans has recorded 234 non-scoring first downs. Add in the 105 1st downs that began every drive, and this means the Saints must have had 339 sets of downs this season.

Let’s look at the Jets for another example. New York has had 126 drives, 153 first downs, and 18 offensive touchdowns. Therefore, the Jets must have had 261 new sets of downs with which to operate.  This methodology should be a pretty accurate way of capturing the number of new sets of downs a team has, although it may be off by 1 or 2 for some teams. (For example, the Jets are probably at 260, not 261; one drive began with an interception but Trumaine Johnson fumbled the return.) You can’t use the actual number of first down plays, because teams often have multiple first down plays due to penalties on the same set of downs (think of a 1st-and-10 where a rusher gains 4 yards and a holding is called, and a team then has a 1st-and-16).

So to calculate the number of sets of downs a team has, you use this formula:

Drives + First Downs Made – Touchdowns

Now how do we calculate the number of drives? That’s pretty simple using the PFR Play Index.

Remember from our work on estimated drives, every drive ends in one of seven ways:

• Punt (could be broken down into punt/punt blocked)
• Touchdown (could be broken down into passing/rushing/fumble recovery)
• Field Goal Attempt (could be broken down into made/missed)
• Turnover (could be broken down into fumble/interception)
• Turnover on Downs
• Safety
• End of Half/Game

Now we often think of a field goal as the end of a successful drive (or at least a non-failure of a drive). But if we are breaking drives down into each discrete set of new downs, a field goal is a bad result.  Consider a team that has a drive like this:

1st-and-10 from the 30: 15-yard gain.
1st-and-10 from the 45: 15-yard gain.
1st-and-10 from the opp 40: 15-yard gain.
1st-and-10 from the opp 25: 10-yard gain.
1st-and-10 from the opp 15: 10-yard gain.
1st-and-G from the 5: gain of 1.
2nd-and-G from the 4: gain of 1.
3rd-and-G from the 3: gain of 1.
4th-and-G from the 2: field goal

Now that would be considered a successful drive. However, under the “new sets of downs” analysis, this drive would be broken down into 5 successful sets of downs (where a team picked up a new first down) and 1 unsuccessful set of downs because it did not pick up a first down.

So obviously a turnover, punt, turnover on downs, or safety is a bad result.  And now we see that a field goal attempt is also a bad result for a discrete set of downs, too.  The end-of-half and end-of-game results should be discarded, IMO, as they are not relevant.  That leaves only sets of downs that end up in touchdowns as successful ones, as touchdowns are in fact first downs.

So to calculate the number of drives, you can either take the number of drives set on PFR and subtract End Of Half/End Of Game drives, or sum the number of drives that result in turnovers/punts/turnovers on downs/safeties/field goal attempts/touchdowns.

Let’s look at the Saints and Jets again.  New Orleans only had one drive end due to the end of a half or game (it appears as though the PFR Play Index automatically discards end-of-game kneel downs).  So the Saints had 104 drives that we want to count, which means they had 338 sets of 1st-and-10 to evaluate.  And we know that New Orleans has picked up 282 first downs.  Therefore, the Saints have picked up a first down on 83.4% of all new sets of downs.  That’s the best rate in the league (and also remarkable).

Meanwhile, the Jets have had 5 drives end due to the clock running out; that brings them down to 121 drives and therefore 256 new sets of downs.  And we know the Jets offense has picked up 153 first downs this year; therefore, the Jets have picked up another first down 59.8% of the time the Jets had the ball on 1st down.  That is the worst rate in the NFL.

This might feel like a familiar metric to you, especially if you’re a Football Outsiders reader.  For over a decade, Jim Armstrong has calculated Drive Success Rate, “which measures the percentage of down series that result in a first down or touchdown. Take-a-knee drives at the end of a half are discarded.”  I’ve often thought that DSR is one of the most underrated measures of team efficiency. I never quite spent the time thinking about how to calculate it on my own, but now that I’ve outlined it above, hopefully it feels more approachable for all of us. ^[1]I’ll note that my numbers are slightly different than Jim’s; I do not know why.

The table below shows this data for all 32 offenses this season. Here’s how to read it, using the Saints as an example. New Orleans has had 24 drives end on punts, 9 drives end on turnovers, 23 drives end on field goal attempts, 0 drives end on downs, 0 drives end on safeties, and 48 drives end in touchdowns. That means the Saints had 104 drives (remember, we are excluding end-of-half/game drives). New Orleans has picked up 282 first downs this year, which means New Orleans has had 338 new series of downs. And the Saints have been successful (i.e., they picked up a first down or touchdown) on 83.4% of those drives.

What do you think? Please leave your thoughts in the comments.