Panthers' pivotal front line play

Star LotuleleiJeremy Brevard/USA TODAY Sports

The San Francisco 49ers enter the divisional round of the playoffs coming off a 23-20 win over the Green Bay Packers that has some pundits calling them the hottest team in the NFL. That's news to the Carolina Panthers, who have won 11 of their past 12 games, with their only loss on the road to playoff-bound New Orleans Saints. The Panthers have also beaten the Saints in that stretch, along with victories over other playoff teams like the Patriots and, yes, the 49ers.

Carolina dominated Colin Kaepernick in Week 10, limiting him to 11-of-22 passing for only 91 yards, with a half-dozen sacks. That performance was no fluke. Carolina's defense has been one of the best in football all year, and its specific strengths and tendencies seem designed to exploit the cracks in San Francisco's offense.

The 49ers run a lot (third in the league with 505 carries), but that doesn't mean they run particularly well. The advanced metrics at Football Outsiders aren't terribly impressed by either Frank Gore or the 49ers' offensive line. That has left the onus on Kaepernick to make plays with his legs -- which has rarely been a problem. Not counting end-of-half kneel-downs, Kaepernick had 80 runs for 533 yards and four touchdowns this season, ranking among the top five quarterbacks in each category. That includes 145 yards on 34 designed runs, but it's what Kaepernick can do when plays break down that really sets him apart.

Kaepernick ran for 388 yards this season on 46 scrambles, while also gaining 563 yards on 79 passes outside the pocket, finishing second to Seattle's Russell Wilson in all four categories. And he's no slouch in the pocket either, averaging 7.8 yards per pass between the tackles, one of the 10 best rates in the league. The best way to contain mobile quarterbacks is to use a heavy dose of zone defense. If you blitz them, you can create running lanes, and defenders in man coverage must turn their backs to the quarterback, meaning they won't recognize running plays until the quarterback is far downfield.

Instead, what you want is seven defenders in zones keeping their eyes on the passer with a four-man rush that can generate pressure on its own, and a speedy linebacker or two to track the QB down if he does escape pressure. The numbers back this up: The San Francisco offense averaged 6.6 yards per play this year when opponents used four or fewer pass-rushers, which ranked a mediocre 13th. That average climbed to 7.5 yards when opponents used at least five pass-rushers, though, and then again up to 8.8 against big blitzes of six or more players, third best in either statistic. Blitzing the 49ers is clearly a bad idea; your front four had better be able to generate pressure on their own.

And that's just how Carolina likes it.

The Panthers don't blitz much, sending five or more pass-rushers on only 28 percent of opposing pass plays, one of the 10 lowest rates in the league. And they big-blitz with six or more defenders only 5 percent of the time. However, just because they don't blitz doesn't mean they don't bring pressure. Carolina led the league in sacks, and finished second in Outsiders' Adjusted Sack Rate, which accounts for pass attempts, quality of opponent and other factors. Greg Hardy finished third in the NFL with 15 sacks, and bookend Charles Johnson added 11 despite missing three games.

The 49ers haven't given up many sacks this year but don't be fooled: They have struggled with pass protection. They finished 11th in sacks allowed, mainly because they didn't pass very often, but they were 22nd in Adjusted Sack Rate.

On the rare occasions when quarterbacks have gotten past Hardy, Johnson & Co., they've usually found speedy linebackers Luke Kuechly and Thomas Davis soon after. Not counting kneel-downs, the Panthers allowed opposing quarterbacks to run 29 times for 167 yards this year, an average of 5.8 yards per carry. They're one of the 10 best defenses in each of these categories. And they didn't just post those numbers against statues. They played four of the top 10 rushing quarterbacks this season (Wilson, Kaepernick, Ryan Tannehill of the the Miami Dolphins and Geno Smith of the New York Jets) and limited them to 106 yards on 16 carries. Meanwhile, they sacked those same quarterbacks 15 times.

This is not to say, however, that the Panthers never blitz at all, only that they do it differently than most teams. They sent defensive backs on blitzes about five times per game this season, and they gave up only 3.7 yards per play on those blitzes, better than anyone except Buffalo. There were six defensive backs in the league this season with at least three sacks, and half of them ( Mike Mitchell, Quintin Mikell and Captain Munnerlyn) played for Carolina.

That could be a dangerous tactic against San Francisco, though. The 49ers faced only 39 DB blitzes all year, the lowest total in the league, and for good reason: They averaged 9.3 yards per play on those blitzes, third best in football.

None of this means that victory for Carolina is guaranteed. The Panthers play copious amounts of zone in part to protect a flimsy secondary, and San Francisco's receivers will have chances to make plays downfield. And it's not as if Cam Newton will have an easy day against the San Francisco defense, either. The 49ers will need somebody to rise up, though, because it's hard to see Kaepernick faring much better against Carolina the second time around.