A two digit numbering system for identifying the offensive skill players on the field at a given time.
The numbered personnel grouping system is used by coaches and players but rarely by commentators and fans. The system makes some assumptions in order to describe the players on the field simply and quickly. The two assumptions are that there is a quarterback and five interior offensive lineman.
Given those assumptions there are five additional players for which to be accounted. Those players can be in the backfield behind the line, running backs. They can be blockers adjacent to the interior line, tight ends, or they can be split out wide as receivers, whether on the line or off.
The first digit explains how many running backs are in the formation; the second digit explains how many tight ends are in the formation. The receivers are not a part of the equation; they are what is left after subtracting the running backs and tight ends from five.
Sometimes it is easier to think of this system in terms of examples. To begin with, if there is one running back and zero tight ends, the number would be 10, called ten personnel.
Here is a formation with 11 personnel, meaning one running back and one tight end.
Here is 20, two running backs and no tight ends.
This is a 22 personnel grouping, two running backs and two tight ends.
The personnel numbering system doesn’t tell you what the formation is, but it tells you what players are on the field. Many different formations can be run from the same personnel groupings.
It tells the defense if the offense is going to be in position to run the ball or throw the ball and allows them to substitute to match. For instance, if the offense has 32 personnel (3 running backs, 2 tight ends) coming on to the field, the defense will want lots of defensive linemen and linebackers to counter, but if the offense has 00 personnel on the field (0 running backs, 0 tight ends, 5 wide receivers), the defense will want lots of defensive backs to cover them.
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