Pro set formation (Offense)

"In American football, the pro set or split backs formation is a formation that was commonly used as a "base" set by professional and amateur teams. The "pro set" formation featured a backfield that deployed two running backs aligned side-by-side instead of one in front of the other as in traditional I-formation sets. It was an outgrowth of the original, three running back T-formation, with the third back (one of the halfbacks) in the T becoming a permanent flanker, now referred to as a wide receiver. ...
A common variant of this formation removes the tight end and replaces it with a third receiver in the "slot" position. The formation is utilized to remove a defensive player from the tackle box to give the offense a 7-on-6 matchup.
There are three formations in the pro set of forms: Pro, Ace, and Tree." [Pro set. Wikipedia]
The American football positions diagram example "Pro set formation (Offense)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.