The first true trend of the season emerged on a weekend in which eight backs had 100-yard plus games and each of their teams won. The trend involves the popular Cover 2 defense that has spread through the league thanks to the success of the Tampa Bay Buccaneers.
For years, offensive minds theorized the best way to frustrate a Cover 2 defense was to gash it with running plays. Gashing defenses with the run was also the answer to Dick LeBeau's zone blitzes. The problem is that running the ball requires patience, and how many offenses have patience these days? It's a passing league in which balance is considered to be 60 percent pass and 40 percent run.
Teams love to spread three, four and five receivers, and watch defensive coordinators try to find enough good defensive backs to match up. Well, Sunday was a breakthrough of sorts that could make this a monster year for running backs. It's one that I didn't think was going to happen until mid-season.
Let's go back to the Browns. Butch Davis used a Cover 2 defense to limit the Colts to nine points in Week 1. In Week 2, the Ravens were going with a rookie quarterback, Kyle Boller, and Davis figured having the safety hanging back in the secondary as opposed to coming up near the line of scrimmage could result in a few interceptions.
Ravens coach Brian Billick loves to pass, but he knows his strength is running the ball. Lewis helped to carry the Ravens to a Super Bowl title a couple of years ago. He's 245 pounds and has 4.4 speed in the 40, having come back from a knee reconstruction. Seeing the Cover 2, offensive coordinator Matt Cavanaugh decided to call running plays until the Browns showed they could stop them.
They never did.
"We love to run against two deep zone," Cavanaugh said. "We figure it's hard to stop our running attack with seven defenders near the line, and if the eighth position is in the deep position, he's not there to stop the run."
Throughout the offseason, my question to coordinators on both sides of the ball was whether the running game would come back in a passing league with so many small quick players on the field. Last year, defenses had their nickel personnel on the field about 65 percent of the time. If more than half of the 11 players on the field are 200 pounds or less and most of them are playing away from the line of scrimmage, how can they handle a big back as powerful and as quick as Lewis?
This is not to say the Bucs defense needs to worry. Their Cover 2 is different than others, and face it, nobody is scoring on them. Dating back to last year, the Bucs have had three shutouts and a no-touchdown game against the Panthers. But it was interesting to see that they lost in a game in which Stephen Davis had 33 carries and 142 yards.
The Bucs aren't a big defense, and their one weakness is going against big offensive lines that can wear down their defensive line. That usually doesn't happen because the Bucs force enough turnovers to prevent teams from getting too comfortable with their running attack.
"The Tampa Bay Cover 2 is different because the middle linebacker drops into the middle of the field to cover half the field," Dolphins coach Dave Wannstedt said. "They have so much speed that it's hard to run on them, and they can stick John Lynch up to stop the run."
Few teams have Tampa Bay's talent, so it's hard to generalize how offenses perform against the Bucs. But a number of teams copied or borrowed Tampa Bay's concepts, and offensive coordinators have to find ways to beat it.
"I call it D-U-H football," Vikings coach Mike Tice said. "If a team isn't going to bring the eighth defender up to stop the run and stay in a Cover 2, I say, 'Duh, run the ball.' When they bring the eighth guy in the box, then you throw it because you are getting some man coverage. That's the way Joe Gibbs used to do it."
What will be interesting to see is how offenses juggle their running attacks. There should be a proliferation of running and 100-yard days. Where teams opened the regular season in more one-back sets, it will be interesting to see if bigger backs don't regain popularity in New England, Pittsburgh and a few other places. With so many defensive backs on the field, some teams went to quick backs such as Kevin Faulk and Amos Zereoue instead of Antowain Smith and Jerome Bettis.
What happened Sunday might give Smith and Bettis hope and a more active role in weeks ahead.
What, you might ask, does this mean for Marshall Faulk of the Rams? Not every team is going to start running the ball 30-40 times a game. Faulk will get more carries this weekend, but that has more to do with the switch from Kurt Warner to Marc Bulger at quarterback than a change in the Rams' offensive approach. Faulk usually gets 21 carries in a Bulger game compared with 17.5 in a Warner game.
Following Sunday's victory over the 49ers, Rams coach Mike Martz snapped at a reporter who asked about running the ball more. Remember, Martz loves sending out receivers and tight ends into routes, so the quarterback has only five blockers in front of him. The 49ers blitzed that alignment, sending six defenders. The extra unblocked defender eliminates a running lane and makes it hard to run.
"You come in my office and you look at tape all week long and game plans and then tell me whether to run or pass," Martz said. "If we keep running when they have eight people up there or they keep blitzing, we are going to lose that football game or lose a running back. That's why they call us coaches."
Obviously, game plans change from week to week. Strategies change from play to play. But what is going on with defenses should be a boost to running backs. More teams are being forced into zone defenses because the influx of big, tall, fast receivers is greater than the number of new cornerbacks coming into the league.
That means that the Cover 2 zone isn't going away. And neither will the different strategies to try to attack it.
The Bucs need not worry.
But some other teams should.
John Clayton is a senior NFL writer for ESPN.com.