The Upshot at the New York Timesintroduces us to the NYT 4th Down Bot, which will tell us in real time whether a team should or shouldn't go for it on 4th down. There's a fairly well-known argument that teams are way too conservative on 4th down. As the 4th Down Bot puts it,
Every week, N.F.L. coaches leave points on the table -- and hurt their teams' chances of victory -- by being too timid on fourth down.
I'm sure this extends to other levels, as well. If teams recognized that the expected value of more fourth-and-short plays is positive and that "four down territory" is larger than they think, we would probably see more conservative play-calling on downs 1-3.
What, therefore, would this do to overall strategy and the value of different position players? It goes without saying that punters and kickers would decline in value as they would be used less frequently. Teams realizing they only need to average 2.5 yards per non-kicking play rather than 3 yards and a cloud of dust would rely more heavily on the run, and we would see more running plays on third-and-long. On offense, running backs and good run-blockers would become more important; wide receivers and quarterbacks would become less important. Defenses would have to focus on the run.
This brings to mind an idea my Dean suggested a few years ago, and it's an idea I'd love to see studied. He suggested putting 3 punt returners back and fair-catching every kick. The probability of an injury is higher on kicking plays than others, as is the probability of a penalty. He wonders--and I wonder--if the expected field position from fair catching every punt is superior to the expected field position from trying to return every punt.