What is the F?

The Colts and the Titans produced some confusion this week as it became clear their offenses feature an “F” position.

It looks unconventional on the Colts’ depth chart, like a “B” is missing on a “FB.” It sounds unconventional in Tennessee, as if it’s replacing one of the traditional receiver spots, “X,” “Y,” or “Z.”

So, as we like to try to do here, I sought clarification.

It’s less complicated in Indianapolis.

Rookie tight end Dwayne Allen is the starting F, and it’s akin to the H-back slot we are more familiar with. He’s the move tight end, who will shift and reset and start plays all over the place -- in the backfield, on the line or even split out.

But when Allen is not on the field as the F, the spot is something different in coordinator Bruce Arians' offense.

Titans receiver Nate Washington played under Arians in Pittsburgh. Per Washington, in a three-receiver set in Arians' system, the F is an outside receiver who runs a lot of double moves and deep routes. In the Colts’ current construction, that should be Donnie Avery or rookie T.Y. Hilton.

In Chris Palmer’s offense in Tennessee, the F is the fullback if a fullback is on the field.

If there is no fullback, it can be a tight end or a receiver.

“In baseball terms, it’s a utility player,” receiver Damian Williams explained. “You’re the guy who’s going to move the most. I actually started off as the F at USC when I was the third receiver.”

Some more explanation from Williams: The F is never on the field if there is not an X (split end) and Y (flanker) on the field, too. In a two tight end set, one of the tight ends is the F, usually the faster, more agile guy (known in this setting as Jared Cook).

"New England, the Giants, the Packers all have a variation of it,” Williams said. “It’s kind of confusing. You’ve really got to know your stuff. It’s more concepts. Constant confusion with moving parts a lot of the times.”

Washington said an F receiver in Tennessee runs a lot of intermediate to short pass routes.

Got it?