San Francisco 49ers Hall of Fame coach Bill Walsh popularized the idea of scripting the first 15 plays of each game.
For the past three decades, many coaches have copied Walsh's script idea. It made sense. As teams got to the end of the week, coaches put together a script that would keep defenses guessing. The plan stressed execution. Quarterbacks and offensive players had a couple of nights to study the script, visualize the successful plays and start the game with a positive tempo.
Fast starts were important to Walsh. He built his great 49ers teams with the idea of getting two scores in the first couple of drives. Working with a 10-0 or 14-0 lead, Walsh then made sure he had enough pass-rushers to pressure a quarterback into mistakes and take opponents out of their rushing attacks.
But even the great Bill Walsh would have difficulty in 2007, when defensive coaches have tried to ruin offensive scripts by using more aggressive blitzes earlier in games.
Offenses that script plays -- especially West Coast attacks such as Seattle, Denver, Green Bay and Philadelphia -- want to get into a good rhythm early in games The idea is to get a long, eight-play touchdown drive mixing in passes and runs and not necessarily a quick-strike score. But defenses have faced that script so long now that they know most of the good teams aren't going to take too many risks in the first quarter while they're working off their scripts.
So defenses this season are willing to take more chances with blitzes on early possessions. Defensive coordinators tested the plan in the preseason, and there has been a carry-over into the regular season. Early blitzes throw off the timing of scripted teams and can create turnovers.
Seattle coach Mike Holmgren admits it's hard to go off the script and go deep against blitzes because no offense wants to start the game with a mistake. That's what happened to Green Bay when Brett Favre was intercepted early in a Week 13 loss to Dallas. Defensive coaches know few West Coast teams are going to throw high-risk passes early in games.
Even the Colts' Peyton Manning is feeling the early heat. Manning adjusts his calls at the line of scrimmage based on what he sees in pre-snap reads. Although it's not advisable to blitz Manning, it's not as risky in the first two possessions when he's testing his play calls and probably isn't going to attack deep.
Consequently, the Colts, who have led the league in first-possession scoring, are 12th this season. In 13 games, they have four touchdown drives and only 27 points on opening drives.
The Seahawks are eighth with 31 opening-drive points. The Broncos are fifth with 34. The Eagles are 11th with 28. The Packers are tied for 21st with 17.
Although the Colts might be down a score or two in the first quarter, Manning doesn't panic. He'll study still pictures of defensive alignments on the sideline and work on his adjustments with offensive coordinator Tom Moore.
By the third series, Manning and most of the top quarterbacks seem to figure out the opponent's plan and attack those weaknesses.
To no one's surprise, the best team on opening drives in 2007 is the Patriots, who don't script plays. They lead the league with 61 points -- seven touchdown drives and four field goals.
Bill Belichick has Tom Brady come out in three- and four-receiver sets and is willing to throw deep to Randy Moss at any time. For the Patriots, it's all about scoring this season. Unlike most teams, they aren't concerned about trying to set up the running game.
Their goal is to get as many points on an opponent as fast as possible, then get the ball back to score more. Sure, that strategy has been criticized as running up the score, but Belichick has a good reason for the plan: New England's defense has holes.
The linebacking corps is old, and it tends to wear down later in games. If a back slips by the defensive line, he could turn a short run into a long one. The Patriots must open big early leads because their defense could lose steam in the second half. Their formula should result in a perfect season.
Of course, offensive coaches will adjust. They will study the early-game blitzes and come up with more aggressive plays in the scripts. It all makes for fun football.
John Clayton, a member of the Pro Football Hall of Fame writers' wing, is a senior writer for ESPN.com.