Stephen Dubner

A running play is more predictable, since the running back has to get through a wall of massive defenders.

But if he does and breaks free into open space, that is a special kind of thrill.

Back when Franco Harris was in the league and for a long time after, many of the game's biggest stars were running backs, and they were paid accordingly.

If you go back 30 years and take the average salary of the top players by position, running backs ranked second, just behind quarterbacks.

This year, running backs ranked 15th.

So what happened?

Everyone knows the NFL has become much more pass-happy these last few decades.

But still, how did running backs fall so far?

As it turns out, I wasn't the only one with these questions.

Roland Fryer, an economist at Harvard and a friend of Freakonomics, wrote a Wall Street Journal column last football season called The Economics of Running Backs.

What is it?

I asked Roland if he would sit for an interview to help answer those questions.

He said yes, but he had another idea that he insisted would be even more fun.

So here's the thing that really puzzles me.

When I called you up and asked if we could talk about your Wall Street Journal column and make an episode based on this idea, you said, yes, and I would actually like to co-host that episode.

Can you explain that?

I know very few Harvard economists or anybody really who's interested in co-hosting a grubby little podcast.

Well, other than that...

I guess the serious question I'm asking is, what kind of questions do you hope to answer or explore as we move forward?

You've got some data, you've talked to a bunch of people, but plainly your appetite is deeper than that.