At some point in the distant past of football the quarterback, halfback, and fullback position were named based on their position behind the center, quarterback being closest, the fullback being furthest and halfback in between.
However at some point halfbacks & fullbacks got switched around in the standard I-formation without their position names being changed. Is there any grand reason behind all this? Nowadays days halfbacks are generally refered to as “running backs” while fullbacks have generally kept their old position name while they still line up in the “halfway” slot.
I recently read David Maraniss’ bio of Vince Lombardi and he quotes Vince as saying “You’re going to be my halfback” to Paul Hornung when he arrives in Green Bay in 1959. I know from seeing old game film that halfback Hornung and fullback Jim Taylor lined up in the modern way so the position change must have occured sometime before the late '50s.
I know that the terms originally designated the distance behind the line of scrimmage each player was - the quarterback was closest, then the halfback, then the fullback. Sadly, I spend entirely too much of my time watching college and pro football. Its rare to hear the term halfback; announcers seem to use tailback and running back more. Fullback, meanwhile, has become a term that describes a guy about the size of a lineman who lines up in the backfield, and whose primary purpose is to be a lead blocker for the half/tail/running back. Some of these brutes have good hands and/or speed and therefore get to run and catch the ball on occasion (you probably knew that, I just liked using the word “brutes”), but mostly they block for running backs or the qb on pass plays.
When the T-formation came into vogue in the 1940s, teams would line up a quarterback under center and then a fullback behind him and then two halfbacks behind the fullback.
Eventually, the second halfback became a flanker as passing increased.
The names now vary depending upon what sort of offense a team runs. Many teams don’t use a fullback anymore as they only employ one running back.