I've asked Hank Gargiulo of ESPN Stats & Information to sift through defensive charting information for performance clues regarding NFC West teams.
Among his findings, with my thoughts as well ...
What they do well: The 49ers appear very stout against the run while in their base 3-4 with seven defenders in the box. The Steelers (2.8 yards per carry) and Jets (2.8) are the clear 1-2 in this area, but the 49ers come in at 3.5, third-best in the league. The NFL average is 4.4 yards.
What they do not do as well: The 49ers stay in their base 3-4 defense a league-high 21.3 percent of the time against three or more wide receivers. San Francisco has not fared well when doing so. The 49ers realize only slight gains against the run in these situations, but they allow an additional yard per pass attempt -- up to 8.1 from 7.1 -- when staying in their base 3-4 against three-plus wideouts. The 49ers also struggle in general against passes traveling at least 15 yards. Opponents have a league-high 108.7 passer rating on these throws.
My thoughts: The 49ers' pass defense hasn't been as good as expected even though the team has gotten younger and more athletic at safety. San Francisco has also faced some top quarterbacks, including Drew Brees, Matt Ryan, Aaron Rodgers and Philip Rivers. Matt Cassel is also enjoying a strong season. Kyle Orton was playing well when the 49ers faced Denver. Sam Bradford was also more efficient back when the 49ers faced him.
What they do well: Arizona has been much better against run and pass when loading the box with more defenders than offenses have available to block them. Against the run, the Cardinals allow 3.3 yards per carry with a loaded box, down from 4.5 when not loaded. The Cardinals allow a lower completion percentage (52.4 vs. 63.1), passer rating (70.8 vs. 85.3), yards per attempt (6.7 vs. 7.3) and yards after the catch average (2.8 vs. 3.3) with a loaded box.
What they do not do as well: The Cardinals' inability to slow down opposing running games out of their base defense with seven defenders in the box hurts them. Arizona is, in some ways, average overall against the run, allowing 4.4 yards per carry. That number balloons to 5.2 per carry against the Cardnials' base 3-4 with seven defenders in the box, third-highest in the league (4.4 is average).
My thoughts: The Cardinals should be much better against the run after using a first-round draft choice for nose tackle Dan Williams. Williams has improved, but 36-year-old Bryan Robinson has continued to start. Any team with Darnell Dockett, Calais Campbell and two big safeties, notably Adrian Wilson, should hold up better against the run. The Cardinals have been weak at linebacker, compromising the defense up front and in the secondary. Campbell hasn't played as well as expected, either, and a shoulder injury has made life tougher for Dockett.
What they do well: The Rams have been above average with their third-down passing defense when they bring in an extra defensive back, especially when the opponent's pass attempt does not go beyond the first-down marker. Using that as our criterion, the Rams are allowing a 42.5 percent completion percentage, good for third in the NFC. The league average is 47.2 percent. The Rams are allowing a 54.0 passer rating in these situations (league average is 69.9). St. Louis' extra-DB packages have also been the best in the NFC West at making sure teams do not gain first downs after catching the ball short of the first-down marker. The Rams allow 34.2 percent of completed passes short of the marker go for first downs. The NFL average is 37.3 percent.
What they do not do as well: Like the Cardinals, the Rams struggle out of their base defense with seven defenders in the box. They allow 5.18 yards per carry in these situations, right ahead of the Cardinals' 5.2 average.
My thoughts: The Rams haven't faced as many elite quarterbacks this season after going against Rodgers, Brett Favre, Peyton Manning, Brees and Matt Schaub when all five were enjoying monster years in 2009. That has helped. The Rams were also stronger than anticipated at linebacker until losing Na'il Diggs to a season-ending injury. Defensive tackle Fred Robbins has been stout, but the Rams need another big interior defender to pair with him. They need help at linebacker, particularly on the weak side. This defense appears well-coached.
What they do well: Their strongest unit appears to be their five-plus DB pass defense, with a caveat. The overall numbers aren't great, including an 84.7 passer rating, which is above the league average (81.1). But Seattle has gotten 22 of its 32 sacks when going with these "small" packages. Opponents are completing only 54.9 percent of their passes against these packages, which ranks fourth in the NFL (60.1 is average). When the Seahawks do allow completions against these packages, however, they tend to be big ones. Seattle has allowed 30 pass plays of at least 20 yards against its small sets.
What they do not do as well: Seattle has struggled against short-to-intermediate passes (those thrown 14 or fewer yards past the line of scrimmage). The Seahawks are allowing a 102.4 passer rating on throws in that range, well above the NFL average of 89.2. Seattle allows 4.7 yards after the catch on these throws, a yard more than the league average and the second-highest figure in the league. If the Seahawks were just average at allowing yards after the catch, they would have allowed about 125 fewer yards on these throws.
My thoughts: The coaching staff has sometimes effectively unleashed creative blitzes with extra defensive backs. Strong safety Lawyer Milloy has led the way. But Seattle has essentially fielded three defenses this season. The first one featured Red Bryant, Colin Cole and Brandon Mebane along the line, providing cover for a healthier Lofa Tatupu at middle linebacker. The second one struggled without two and sometimes three of those linemen. Tatupu's health also deteriorated. The third defense has Cole and Mebane, but no Bryant, who is on injured reserve. The Seahawks have tried to adjust. They tackled much better against the Falcons.