Using data from Pro-Football-Reference for the 2016 NFL season, I calculated the average number of snaps per play taken by players at each position across the league. Here are the numbers for offense:
QB: 1.00
RB: 1.10
WR: 2.60
TE: 1.25
OT: 2.05
OG: 2.00
OC: 1.00
Some of these are pretty obvious: you have exactly one quarterback, one center, one left guard, and one right guard on each play. For the most part, you have two tackles, although occasionally teams will have three tackles on the field (apparently, about once every twenty plays).
The more interesting numbers come in the split among the skill position players: running backs (including fullbacks) only get about 1.10 snaps per play; in the ’70s, that number would be much closer to 2.0, although there’s no way of getting more precise than that. Tight ends are at 1.25, while the average play in 2016 featured more than 2.5 wide receivers on the field. Three wide receivers has become the base formation in the NFL.
On defense, it’s harder to get reliable results. Some defensive ends are defensive ends; others are defensive tackles in some systems and outside linebackers in others. As a result, I think the defensive end numbers here may be a little light, but here were the numbers as calculated using PFR’s positional designation:
DE: 1.57
DT: 1.59
LB: 3.06
CB: 2.62
S: 2.16
I think the high-level takeaway is that there are 4.78 defensive backs on the field on each play, meaning we are moving closer and closer to nickel being the true base defense.
What can we do with these numbers? Well, a lot of things, I’m sure. Perhaps you can throw out some ideas in the comments. Here’s one thing we can do: calculate the draft value used on each position in the 2017 Draft, and adjust it for the number of players on the field in a given play:
| Pos | Draft Val | % of Draft Val | % of Snaps | Ratio |
|---|---|---|---|---|
| RB | 131 | 9.2% | 5% | 183.0% |
| DE | 186.2 | 13% | 7.1% | 182.3% |
| QB | 95.2 | 6.7% | 4.5% | 146.3% |
| CB | 196.9 | 13.8% | 11.9% | 115.5% |
| S | 155.8 | 10.9% | 9.8% | 110.9% |
| WR | 185.2 | 12.9% | 11.8% | 109.5% |
| TE | 87.1 | 6.1% | 5.7% | 107.1% |
| LB | 187.2 | 13.1% | 13.9% | 94.0% |
| DT | 66.7 | 4.7% | 7.2% | 64.5% |
| OT | 64.9 | 4.5% | 9.3% | 48.7% |
| OG | 55.9 | 3.9% | 9.1% | 43.0% |
| C | 19.3 | 1.3% | 4.5% | 29.7% |
By this method, no position was as highly valued as running back, which is obviously weird. Seeing defensive end and quarterback in the top 3 makes sense, and seeing center and offensive guard at the bottom makes sense. But running back at the top? That is unusual, which is why I wrote that the 2017 Draft brought back the running back position.