Leadership is fascinating because it’s rooted in mystery. What makes certain leaders great? What makes them tick? How do they know the right thing to do?

One way to approach the mystery it through the window of a small question: why did so many mailroom workers rise to become CEOs?

Here’s a partial list:

• Dick Grasso (NYSE)
• Barry Diller, Michael Ovitz, and David Geffen (William Morris)
• Mike Medavoy (Universal)
• J. Lawrence Hughes (William Morrow)
• Ned Tanen (MCA)
• Jeffrey Katzenberg (Paramount)
• George Bodenheimer (ESPN)
• John Borghetti (Quantas)
• Tom Whalley (Warner Bros.)
• Sidney Weinberg (Goldman Sachs)

Other mailroom workers-turned-leaders: Don Hewitt (60 Minutes), John Bachmann (Edward Jones), and Simon Cowell (EMI records). If you Google the phrase “started out in the mailroom” and “ceo,” you get 3,450 results.

This is a striking pattern, because it’s so unlikely. At most corporations, the mailroom is the bottom rung. Its duties are simple: you read and sort letters, photocopy, roam the building delivering the mail, fetch coffee. To become CEO, the mailroom group had to do a very difficult thing: they had to outcompete hundreds of employees who were 1) more qualified, 2) better-resourced, and 3) more highly regarded – since after all, they weren’t relegated to the mailroom. And yet despite those immense odds, these underdogs pulled it off. How?

I think part of the answer can be found by looking at the equally demanding world of the NFL – specifically the surprising career paths of current head coaches. Because it turns out that an unusually high percentage  (nine at last count, including the Tony Sprarano of the Dolphins, Brad Childress of the Vikings, and Mike McCarthy of the Packers) share an interesting quirk on their resume: they sll started out on the bottom rung of the pro-coaching ladder, working as quality-control coaches.

Quality-control is not a sought-after job. It’s frequently the lowest-paid member of the staff. Q-C coaches spend their days sitting in a room watching game tape, compiling data, analyzing film, producing 50-page scouting reports for coaches to use, and, yes, occasionally fetching coffee for the “real coaches.”

“We worked quadruple everybody else, but we got to feel like a coach,” said Todd Haley, now the coach in Kansas City, who worked in quality control with the Jets. “We had responsibility. It’s the greatest job in football as far as learning.”

We usually think of leadership as being an innate talent, stemming from such intangibles as “charisma, “vision” and “character.” But the success of these underdogs from the mailroom and Q-C  coaching flips this idea on its head. The leadership talents of these CEOS and NFL head coaches is not being born; it’s being grown. They are positioning themselves smack-dab in the middle of the information flow, and they are working that flow like a training session to change their brains.

To understand how this works, let’s look at a typical day in the life of a mailroom worker and compare it to that of a higher-up.

The higher-up is insulated in their job, cocooned by the responsibilities of the day. Their advancement depends on performing a narrow job well and being recognized for doing so, usually by his or her immediate boss.

The mailroom underdog, on the other hand, roves around like a spy, able to peer into the organization’s inner workings (not least by reading mail and hearing gossip). They are the proverbial fly on the wall inside the offices of the powerful. They can learn the anatomy of disasters and successes. They can navigate a maze of personalities; witness communication skills. They can learn the crucial dividing line between what matters and what doesn’t. Their advancement doesn’t depend on performing a narrowly defined task for a narrow audience; rather, it depends on their impressing someone – anyone, really – of their general-purpose savvy and chutzpah.

In short, the underdog isn’t really an underdog — they’re the overdog. For a person of the right mindset – like former Paramount/Fox CEO Barry Diller – this spot is the perfect neural-training camp.

“My great strategy was to take what was seen as the worst job in the building — photocopying I’d collect things to copy, along with as much of the file room as I could carry, and hole myself up reading through the history of the entertainment business as seen through every deal, every development, every contract I read their entire file room.”

That’s not to say personal characteristics don’t count, because they do. Diller, like all of these successful underdogs, is hugely ambitious, persistent, and hardworking to the extreme. But here’s the point: so are a lot of other people. These underdog groups succeed in disproportionate numbers because they channel that energy through a grid of intensive training to make their brains fast, accurate, and organization-smart.

An increasing number of companies seem to understand this. GE’s Crotonville Leadership Development Center is a now-legendary pioneer in this area. Hindustan Unilever, a hugely successful Indian company, is widely regarded as a talent hotbed –largely because its senior managers spend 30 to 40 percent of their time mentoring young leaders.

So what’s the takeaway from all this? It depends who you are.

For organizations:

• Construct a virtual mailroom,  a training program that allows young employees to learn – through real-world experience, not lectures – how leadership really works.
• Consider leadership-mentoring programs.

For individuals:

• Judge early jobs by their position in the information flow, not by prestige or salary.
• Create your own training regimen. Whether it’s photocopying contracts or making predictions and seeing how they turn out, it doesn’t matter so long as its yours.