Nowadays, quarterbacks wear a condensed version of their teams' playbooks on their wrists.

Professional football has seen its fair share of changes over the decades; some bigger than others. The forward pass, which was illegal in the sport's early days, is perhaps the best example. Once instituted, it changed not only the game but ultimately the role of the quarterback.

However, changes over the past half-century or so have taken place in more incremental steps than dramatic transformations. Merlin Olsen, the Hall of Fame defensive tackle who was a member of the renowned Fearsome Foursome during his career with the Los Angeles Rams (1962-1976), reflected on some of the specific ways in which the game has been altered during that time period.

"I think the two things that have changed the game most are money and technology," he said. "In the sense that the game is much more sophisticated today, and part of that is because of the advent of the computer. In the past, intelligent defenses would break down their live scouting reports and later they would analyze what people were doing.

"Now teams are so sophisticated at scouting themselves, week to week, they know what information is being assembled about that, and they will use that against their opponent. Just like their opponent will use it against them.

"You used to have to scout these games and mark all this stuff by hand and go through and evaluate. Now the computer will do it for you, and you suddenly have all these potential tools that you can use. Now you have to figure out a way to turn the tables and negate that kind of information [that your opponent has]."

On the offensive side of the ball, the pattern tree has remained fairly similar, with the same basic routes still in place. However, what has changed is how the routes and plays are executed.

"Now, everything is based on what is happening in front of the receiver," Olsen outlined. "He may have five different routes he will run on a given play depending on what the defensive backs and linebackers are doing in front of him. The responsibility of players having to respond to what is happening in front of them instantly is much more sophisticated and much more technologically difficult than it was when I was playing.

"The real pressure falls on the quarterback because he's got to read it perfectly and he's got to know exactly where all those receivers are. The mental responsibilities were great for the quarterbacks in the 1960s; they're incredibly huge now. It's not the kind of thing you'd even try to do if you weren't capable of a tremendous amount of visualization and memory."

The added complexity on offense has naturally translated into comparable alterations on defense. Defenses have to be prepared to react in a variety of ways depending on whether the quarterback takes a three-step drop, a five-step drop, rolls out, hands off, etc.

"Defensively we had to deal with lots of formations," Olsen said, "but it wasn't as sophisticated as it is now. The things they're doing now (on offense) as far as motions, moving tight ends back and forth and then shifting the backfield, you literally have three or four shifts in power on a single play, and of course that puts incredible pressure on the defense. Most defenses are trying not to react to each of those shifts. They'll change what they're doing, but they're not trying to move people clear across a formation."

The basic formations are still in use, but it's the way in which each one is tweaked and presented that are different.

"One of the most important things you do is disguise your defense and convince the QB that you're going to do one thing and end up doing another," Olsen explained. "Of course, the offense is doing the same thing to you. The game of bait and switch is much more sophisticated. We did it and we thought we were pretty fancy with it, but certainly we were amateurs compared to what they're doing today."

The Rams defense that Olsen played with was considered pioneering when it came to running stunts that were incorporated into the basic defensive packages. They were also one of the first teams that included those stunts as part of their actual blitz packages.

But the basics of the game have remained the same. Hall of Fame head coach Marv Levy summed it up.

"Football has changed in many ways strategically and tactically, but the same things that won when the game first started are the same things that win now. If you run, throw, block, tackle and kick better than your opponent, you'd win in 1926 and you'll win in 2006."