keep a very basic chart for both teams, and for every possible personnel grouping—from an empty backfield with five receivers (00 personnel) to a jumbo lineup with two backs and three tight ends (23 personnel)—I mark how many times each team ran or passed the ball.

personnel. If it sends out one back and two tight ends, it’s 12 personnel.

Personnel groups are identified by the number of running backs and tight ends on the field on a given play, in that order. If a team sends out two running backs and one tight end, it’s called 21