BALTIMORE - All week, the primary question was how the Patriots would alter their defensive approach with outside linebacker Rosevelt Colvin lost for the season with a foot injury.
Would it mean more playing time for Junior Seau, a super sub off the bench, in the base 3-4 alignment? Would Adalius Thomas move from inside linebacker to outside linebacker? Would younger players Pierre Woods and Eric Alexander step in? Would there even be a scheme switch from the 3-4 alignment to the 4-3?
While all the options were dissected and analyzed, perhaps there was too much of an assumption that while the players might change, the performance wouldn't.
That is not to suggest the Patriots' defensive struggles last night against the Ravens wouldn't have occurred if Colvin had been in the lineup. Colvin alone isn't that much of a difference-maker, and his absence doesn't explain why a stout defense was suddenly on its heels against one of the NFL's more offensively challenged teams.
But when one player is removed from a sturdy front seven, it can have a residual effect on the other six players - specifically in the running game. That could be seen last night.
The Patriots opened in a 4-3 - with Jarvis Green the extra lineman in place of a linebacker - and the results were disastrous.
By the middle of the Ravens' third drive, the team was in a 3-4 - with Adalius Thomas in Colvin's spot on the outside opposite of Mike Vrabel, and Junior Seau and Tedy Bruschi paired in the middle - and it pretty much stayed there the rest of the way.
The results weren't much better.
If there was a common theme throughout, it was that the Patriots were gashed on the ground, overpowered at the line of scrimmage. The Ravens finished with 166 yards on 37 carries (a 4.5-yard average), with Willis McGahee leading the way with 138 yards on 30 carries.
While there was relief after the game that the Patriots pulled out the 27-24 victory, the defenders didn't hide their disappointment with the effort.
"We just can't win if we allow teams to just come in and pound the ball on us," safety Rodney Harrison said. "That is something we always have pride in, and we just can't let that happen. We will get it corrected.
"We can't allow teams to come in and say, 'You know what, this is mano-a-mano and we're going to knock you in the face and run the ball.' And that's what they did."
One of the hallmarks of the Patriots' defense is stopping the run, thus making the opposition one-dimensional, but the Ravens chewed up New England with a bulldozing ground game. And while the Ravens' hard-charging style should not be overlooked, of primary concern was that the Patriots' linemen struggled to hold ground up front, while the linebackers weren't consistently filling their gaps.
It was a breakdown not often seen from the team's front seven, which was operating without Colvin for the first time this season.
"They opened some holes, we missed some tackles, and we were out of position. It was a combination of everything," nose tackle Vince Wilfork said.
When Colvin (foot) was placed on season-ending injured reserve last Tuesday, the Patriots had concealed their intentions as to how they would fill the void.
They went 4-3 out of the chute last night.
The four-man line consisted of Green and Ty Warren at end, with Richard Seymour and Wilfork inside at the tackles. Behind the big boys up front, Bruschi manned the middle linebacker position, with Vrabel and Thomas on the outside.
The Patriots had played the 4-3 before, primarily against the Bills Nov. 18, so it wasn't as if this were a major overhaul. And because the Patriots pride themselves on being able to switch their approach from game to game, drive to drive, snap to snap, such a change wasn't supposed to open such large running lanes.
"I don't think it was any magic, they did a good job blocking, a good job running, had a good scheme, and challenged us some on the off-tackle and cutback areas," coach Bill Belichick said.
A pattern began to develop on the Ravens' second drive, after a 53-yard completion to receiver Devard Darling (aided by a missed tackle by Brandon Meriweather in the dime defense) advanced the ball to the Patriots' 18-yard line. At that point, Baltimore handed off to McGahee on the next three plays, and he gained 3 yards, 6 yards, and 1 yard to move the chains.
Seldom is the Patriots' defense overpowered at the point of attack, but the Ravens were pushing through New England at the line. Then, as the defense attempted to tighten up in the front seven, Kyle Boller hit them through the air, on a 4-yard pass to Derrick Mason, before threading a pass in to Mason for a 4-yard touchdown.
The Ravens also moved the ball into position on their third drive, marching 12 plays and 55 yards to set up a 29-yard Matt Stover field goal. Once again, the 4-3 defense had too many leaks in the running game, with McGahee busting for 15 yards on second and 8.
The Patriots' spotty performance ultimately led to the switch to more of the 3-4. While the team liberally switches from the 4-3 to the 3-4 at times, this change didn't appear to be by design.
If there was a bright spot, it was that the defense made the plays it needed to at the end of the game, to give the offense a chance to put together its improbable winning drive. But that didn't overshadow an otherwise disappointing effort, specifically against the run.
"Stopping the run is one thing we pride ourselves on," Wilfork said. "It didn't happen tonight."
Mike Reiss can be reached at mreiss@globe.com.
