Nationally, the face of the Seahawks is Shaun Alexander, the NFL's top rusher.
Alexander, who came within a yard of winning the rushing title last year, is the king of fantasy football for his ability to score touchdowns in bunches. But this is where reality meets fantasy. As important as Alexander has been to the Seahawks' run to the NFC Championship Game against the Panthers, the heart of Seattle's offense is its three-receiver sets.
Coach Mike Holmgren runs the pure version of the West Coast offense he learned from Bill Walsh when he was with the San Francisco 49ers. Many of Holmgren's disciples -- such as Steve Mariucci, Andy Reid, Mike Sherman, Jon Gruden and others -- have created hybrids, which don't regularly feature the three-receiver formations commonly utilized by Seattle.
Holmgren bases so much of his strategy off three-receiver sets. Alexander led the NFL with 1,880 rushing yards, but what's amazing is that half of those yards came out of three- and four-receiver sets.
"With three-receiver sets, you spread the field," center Robbie Tobeck said. "Sometimes, we'll do some run-and-shoot. We'll sit back with one back and four wide receivers and do that. I remember the run-and-shoot in Atlanta. We always had a 1,000-yard rusher every year. We had a 1,000-yard rusher because we spread the field. There are running lanes open, and Shaun is a great open-field runner."
With their various packages, the Seahawks use the pass to set up the run. Holmgren can go with two tight ends to pound the ball. He'll use the conventional two-receiver, two-back sets. He'll spread the field with four receivers or occasionally go with an empty backfield. Holmgren won't use shotgun formations much, as Walsh did, because he doesn't believe in it.
The amazing part of Seattle's offensive success this year is what's happened to the three receivers. While quarterback Matt Hasselbeck continues to excel, Seattle was forced to make changes in the receiving corps. Gone from last season is Koren Robinson, the ninth overall pick in 2001 whose alcohol problems led to his release. The team's best receiver, Darrell Jackson, missed 10 regular-season games with knee problems.
Holmgren had to patch his three-receiver set. He had his best slot receiver, Bobby Engram, play split end, normally a position occupied by the team's speediest receiver. Tall, dependable Joe Jurevicius became the possession receiver during Jackson's absence. Holmgren used the time Jackson was out to develop D.J. Hackett as a deep threat. And Seattle tried to use former Bengal Peter Warrick in the slot.
"We had Peter Warrick on the sidelines in street clothes, and he's a phenom," Jurevicius said after Saturday's 20-10 victory over the Redskins. "I think we have a talented room. We feed off each other. There is no animosity "
This season, the Seahawks replaced potential with production. For three years, the Seahawks led the league in dropped passes. This receiving group cut the number of drops roughly in half from last season. Because of Jackson's injury, there were no 1,000-yard receivers. Engram caught 67 passes for 778 yards; Jurevicius caught 55 for 694; Jackson 38 for 452; Hackett 28 for 400; and Warrick, who played sparingly, 11 for 180.
The interesting phenomenon has been Holmgren's play-calling. He has enough confidence in whatever receiver is on the field that he will call plays out of three-receiver sets that others might shy away from. Without Jackson, the Seahawks' receivers lack down-the-field speed. But if Holmgren likes a particular play for a certain time, he'll call it -- regardless of the composition of the three-receiver set.
"Sometimes, you'll look at the sheet or on the PowerPoint presentation and say to yourself, 'Is it going to work?"' Hasselbeck said. "It does."
What works best, though, is Alexander running out of three-receiver sets. It's become a staple of the offense. Seattle's favorite play is what the team calls a "Blast." It's usually run to the left, and it's often called from an audible.
The plan is simple. The three-receiver set makes the defensive coordinator decide whether to use a linebacker or a defensive back to cover the extra receiver. That usually takes a defender out of the tackle box, making it easier to run. Hasselbeck will go to the line of scrimmage and spot the defensive alignment.
If the strength of the defense is to his right, he'll call an Alexander run to the weak side of the offense, which actually plays to the strength of the offense. On the left side of the Seahawks' offensive line are two starting Pro Bowl blockers: tackle Walter Jones and guard Steve Hutchinson.
"When we're in the huddle and none of the other runs are working, we'll say, 'Let's run Blast,'" Tobeck said. "We have a couple of plays we can run off that. I just think it fits our offensive line well. The three-receiver set spreads those guys out. It's a play we have confidence in."
Alexander averaged 5.5 yards per carry out of three-receiver sets, according to Stats Inc. When he ran plays out of four-receiver sets, he averaged 5.6. Those plays accounted for a combined 169 carries and 936 yards.
Running that much out of three-receiver sets creates a rare balance on plays normally designed for the pass. Plus, the ability to audible from pass to run out of those formations keeps defenses guessing. Not only has Alexander been successful on three-receiver running plays, but Hasselbeck also has been better as a quarterback.
His completion percentage out of three-receiver sets is 67.3 percent, and he's averaging 7.55 yards per attempt (on 205 such attempts). He's thrown for 10 touchdowns out of three-receiver sets.
"The three-receiver sets can put pressure on defenses because you have two solid backs in the backfield and good receivers," Engram said. "It makes defenses play cat-and-mouse with us whether they bring a linebacker on the field or if they bring a defensive back on the field. Coaches do a good job of mixing the plays and taking advantage of what they have on the field."
John Clayton is a senior NFL writer for ESPN.com.