FOXBOROUGH - Like many teams, the Patriots have generally followed a three-step process that has contributed to their winning ways in recent years.
First, they focus intensely on their breakdowns and areas that gave them the most trouble. Then they identify why it happened and practice it. The final step is making those corrections on the field in the next game.
At this point, the Patriots are in the midst of Step 2.
It didn't take them long to pinpoint run defense as the primary trouble spot in Monday night's win over the Ravens. The next part of the equation, then, was answering why their normally sturdy defense was shredded for 166 rushing yards, the second-highest total allowed by the Patriots this season.
Were they simply overpowered? Did the Ravens uncover a weakness? Or was it something else?
Finding the answers, and correcting the problems, seemingly takes on added importance because the Steelers, who invade Gillette Stadium Sunday, have run the ball more than any team in the NFL (405 carries).
If run defense is suddenly a chink in the Patriots' armor, the Steelers and running back Willie Parker (No. 2 in the NFL with 1,093 yards) pose a huge threat.
After Patriots defenders concluded film review and met with the coaching staff this week, the most prevalent answer was a lack of discipline. They were caught out of position too many times and didn't always play their gap responsibilities and technique correctly.
It came down to a lack of execution in what Bill Belichick often refers to as "run fits." A run fit is defined as the gap a player is assigned to fill at the line of scrimmage - and when each defender has the proper fit, it can create a wall that is tough to break through.
"With any run defense, it has to deal with gap control," said inside linebacker Junior Seau. "If there is someone in a gap, there won't be any vacancy that a running back can run into. We have to hone down on those gaps and make sure we're in the right position to make a play whenever it's asked to be made. It's really as simple as that.
"There is no hidden science method you can go about to learn about gap control. There are the A, B, C, and D [gaps], and someone has to be in those gaps. So be there."
The A gap is between the center and guard, the B gap between the guard and tackle, the C gap between the tackle and tight end, and the D gap between the tight end and outer edge of the field.
A review of the four longest runs allowed by the Patriots Monday night - gains of 15, 11, 18, and 17 yards by Willis McGahee - reinforces Seau's point.
On the 15-yard run, which came in the second quarter, the Ravens brought receiver Mark Clayton in motion on an apparent end-around, but McGahee got the ball and surged up the middle between the center and guard. The Patriots were in a 4-3 alignment and the three players seemingly responsible for that area - defensive tackles Vince Wilfork and Richard Seymour, and Seau - were either out of position or blocked.
On McGahee's 11-yard run at the start of the third quarter, the Patriots were in a 3-4 and the Ravens called an off-tackle run to the left. Outside linebacker Adalius Thomas appeared to do his job, standing up the tight end and keeping the play from going to the outside, but McGahee cut inside, causing the Patriots problems. Inside linebacker Tedy Bruschi was blocked by mammoth left tackle Jonathan Ogden, leaving an open gap for McGahee, who powered through and turned a 6-yard run into an 11-yarder.
The plays provided a contrast to the team's problems in run defense.
In some cases, the Patriots simply weren't filling the correct gaps because of a breakdown in discipline and technique, or overpursuit. In other cases, they couldn't fill them because the Ravens beat them with solid blocks, and McGahee ran through some tackles.
The performance didn't sit well with Patriots defenders Monday night. It still didn't yesterday.
"We're too good, we have too many good players, to play like that," said outside linebacker Mike Vrabel, one of the team's captains. "I think everybody has to step up and play better, right across the board. It's not one guy. It's every single person."
As the Patriots prepare for the Steelers, they do so knowing that Monday's performance was the exception more than the rule. The Eagles totaled just 48 rushing yards the week before.
The Patriots rank sixth in the NFL for fewest rushing yards allowed per game (92.8), although opponents are averaging 4.1 yards per carry (19th in the NFL).
Surely, they will be tested by the Steelers, who are third in rushing yards per game (138.3), and tied for 11th in average yards per carry (4.1).
"They're committing to running more than most teams in the NFL," Vrabel noted.
Which puts an even brighter spotlight on Step 3 of the Patriots' process.
They identified run defense as a primary problem. They think they know why it happened.
Now, it's about rebounding in a game, against one of the NFL's best running teams.
Mike Reiss can be reached at firstname.lastname@example.org.