For those looking for a definition to the scheme... here you go.. and it will maybe help dispell the illusion that any running back can be successful in the scheme. To me the running back needs to have great vision, decisive decision making, instincts and a decent burst to utilize the scheme.
But Warhawk's point above to me is correct.. you have to have the correct personal to run the scheme, the lineman have to be athletic and be able to make reads at the line. Additionally they have to be able to get out of their stance quickly.
The running game in football used to be pretty simple. The most complex things you would see for line play were some pulling guards to run sweeps or traps. But then several years ago you began to hear the word zone get thrown around more and more frequently (with the likes of Denver, Atlanta and others adopting it... yes us too) until it's about all you hear anymore.
In a general overview this is how a zone should be blocked, but I won't pretend to be an expert, but I will try to explain the basics to simplify things a bit. In the offense you and I grew up in, most of the time the running back had a specific point to try to run through, and the OL tried to create a seam right in that spot. Called man or drive blocking, requires more strength and doesn't require as much agility because everything happens in front of you.
With zone, you don't tell the running back exactly where to go. You direct his first couple of steps, and the point at which he gets the hand-off from the QB, but from there it's his responsibility to find a seam. Hence the "one" cut and go mantra that you hear about from the coaches.
There are a couple different kinds of zone, two of the most common being the inside zone and the zone stretch.
The "inside zone" is more of a downhill attack, and is more likely to produce the cutback lane. The back must be able to read the progress of the play and cut and go.
The "zone stretch" does just what it sounds like - runs more towards the edge, trying to get defensive flow horizontally so a vertical seam can be created, moreso of the drive or man scheme. Big play potential here.
Blocking the zone is where it really helps to have athletic linemen who can move horizontally with decent power and push. In fact, the OL must be able to move horizontally, all while keeping their shoulders square to the line of scrimmage and while engaging the defense. If they open up their shoulders at all, at can create a seam for the defense to get penetration and disrupt the play before it starts.