3rd downs may decide Super Bowl

Seattle SeahawksMark J. Rebilas/USA TODAY Sports

Every Super Bowl winner needs a key stop on defense at some point during a postseason run. Getting a stop on third down remains the most common way of ending an offensive possession in the NFL and it should be a big factor for both teams in Super Bowl XLVIII. While the team that converts at a higher rate on third down is only 7-7 in the past 14 Super Bowls, these games often swing on one or two crucial third-down situations.

Fans of the Seahawks should understand this very well. In Super Bowl XL, Pittsburgh's Ben Roethlisberger converted a third-and-28 -- the longest third-down conversion in Super Bowl history -- with a 37-yard pass to Hines Ward. The Steelers went on to score a touchdown and never trailed again. Seattle quarterback Matt Hasselbeck threw an interception on third-and-18 in the fourth quarter and the Steelers put the game away with another score.

Broncos QB Peyton Manning is also familiar with big third downs. With a 10-3 lead in Super Bowl XLIV against New Orleans, he watched Pierre Garcon drop a critical pass on third-and-4, setting in motion events that led to Manning not throwing another pass until the third quarter, after the Saints used a surprise onside kick to take the lead. In the fourth quarter, Manning's third-and-5 pass with the Colts down 24-17 was intercepted and returned 74 yards for a game-clinching touchdown by Tracy Porter.

In 2014, Manning will look for redemption against a historically stingy Seattle pass defense. Meanwhile, the Denver pass defense has been the worst in the league on third down, setting up a Super Bowl that would seem to favor the Seahawks in crucial situations, but let's break down the tape and numbers to see who really has the advantage.

Denver offense versus Seattle defense

This is a matchup of strengths. Denver has not played a defense as tough as Seattle's this year and Seattle has not played an offense as great as that of the Broncos. For teams that are so unfamiliar with one another, this chess match should be magnificent to watch, assuming the weather does not severely hinder the quality of the game.

Football Outsiders uses a DVOA rating ( explained here) to measure how efficient teams are on each play in the context of that game situation. When it comes to the best pass defenses on third down since 1989, the Seahawks rank No. 1 (out of 765 defenses) with an incredible minus-78.9 percent DVOA (a negative number is better for defense). The Broncos are no slouches on third-down passing offense, ranking third in 2013 with a 62.7 percent DVOA.

Denver's offense ranked second with a 47.3 percent conversion rate and the Broncos' average third-down attempt came with 6.3 yards to go for a first down. Only San Diego (6.2) and Indianapolis (6.2) did a better job of making third down manageable. In the playoffs, Denver has turned into a ball-control offense, averaging 8.0 drives per game compared to 12.0 in the regular season. The key to that change has been converting 16 of 26 third downs (61.5 percent), which could have been even better without three dropped passes and a lost fumble (or so it was ruled) by Julius Thomas against San Diego. Unsurprisingly, Denver's had to punt only once on 16 postseason possessions.

Seattle's defense ranked only 11th in overall third-down conversion rate (35.3 percent), but allowed a league-low 4.1 yards per play on third down. In the playoffs, the Seahawks have allowed only 6 of 23 third downs (26.1 percent) to be converted and the longest conversion was on a third-and-5.

Nearly 80 percent of third-down plays are passes in the NFL, so this matchup heavily relies on Manning's pre-snap reads against a defense that rarely blitzes overall -- 64.9 percent of third-down pass plays saw the Seahawks rush three or four defenders -- but can blitz effectively.

On third down, Seattle has allowed the fewest touchdown passes (two) and intercepted the most passes (12), however it must be noted that Carson Palmer was responsible for five of those 12 interceptions. On third down, Manning's thrown a league-best 14 touchdown passes and including the playoffs has converted 47.3 percent of his attempts.

Seattle was able to put the quarterback under duress on 38.5 percent of third-down pass plays, including 20 sacks. Manning's been sacked on seven of his third downs and put under duress only 20.1 percent of the time (converts 21.2 percent of plays when pressured). Pressure is a must, because Manning's four primary receivers each have 31-40 targets on third down, so he'll sit back and make the open guy his weapon of choice -- regardless of who it is. That's why Manning will gladly let Richard Sherman, who primarily plays on the defense's left side of the field, lock up one receiver. He has numerous options and no favorites.

If the weather conditions are really poor, Denver may find running the ball on third down to be both a necessity and an advantage. Seattle ranks only 17th in third-down run defense DVOA and 19th in conversion rate (53.3 percent). Excluding a kneel down, Seattle faced 44 runs on third down in the regular season. Seventeen of the runs were by a quarterback and a dozen were scrambles. That's never a concern with Manning. When the Broncos run, attacking the right end should be the plan. Seattle's defensive line ranks 24th in Adjusted Line Yards (explained here) on runs to the right end while Denver's offense ranks seventh on those runs.

One of Denver's best plays against New England was Manning's audible to a run on third-and-10 that produced a 28-yard gain to the right by Knowshon Moreno. While Manning is unlikely to get away with another "Montana Fat Man!" audible for that draw, he can just change the name to something else this time. His willingness to let the running game do the dirty work against this great pass defense is one of the biggest factors to Denver's success.

If Manning's forced into a lot of third-and-long situations (needing 8-plus yards for a first down), he has been very impressive, converting 27 of 70 plays (38.6 percent). But Seattle leads the league there, allowing only 2.9 yards per play and a 14.5 percent conversion rate on third-and-long passes. If we include the playoffs and look when it gets to third-and-11 or worse, quarterbacks converted once out of 39 plays (2.6 percent) against Seattle.

However, it was just one season ago when the Seahawks' defense ranked dead last in the league on third-and-long, allowing a league-worst 36.4 percent conversion rate and 32 first downs. Things can change quickly in the NFL. Just ask the Broncos.

Seattle offense versus Denver defense

Last season, Denver was dominant with a minus-66.9 percent DVOA on third-down pass defense (which also includes fourth downs), the fourth-best mark since 1989. But that defense is best remembered for Rahim Moore misplaying the ball on third-and-3, allowing Jacoby Jones to catch a 70-yard touchdown with 31 seconds left in a bitter loss to the Ravens.

That was one play, but the Broncos have fallen all the way to the bottom of the league in third-down pass defense in 2013. Denver's minus-40.0 percent DVOA ranks 744th since 1989, meaning a drop of 740 spots in one year. Even more concerning is the fact three of defensive coordinator Jack Del Rio's defenses (two when he coached Jacksonville) rank in the bottom 22. Without pass-rusher Von Miller or cornerback Chris Harris, Denver would seem to be at a serious disadvantage, but this defense has held up in the playoffs against San Diego and New England.

Of the 10 third-down conversions against Denver in the playoffs, seven came in the second half with Denver ahead by at least 16 points. The defense is getting off the field early in the game and allowing the offense to take control.

That will be critical against a Seattle offense that is just mediocre on third down: 17th in conversion rate and 18th in DVOA (14th in third-down passing DVOA). Russell Wilson has converted 36.9 percent of his third-down plays this season, including the playoffs where he is 7-of-22 (31.8 percent).

Ever since a brilliant performance in Week 13 against the Saints, Seattle's offense has sputtered and third down is part of the struggle. Since Week 14, Seattle's offense has converted only 30.4 percent of its third downs, ranked 30th in the league in that time.

Most of Marshawn Lynch's meaningful third-down carries come on third-and-short. Needing 1-2 yards, he converted on 8 of 13 runs. That's better than his career average, which is surprisingly low at 52.9 percent. On third-and-short, this matchup is a push with Denver's defense ranking 17th and Seattle's offense ranking 19th.

This matchup also comes down to the quarterback. Seattle has not been methodical on offense, but has hit on big plays and taken advantage of opponent mistakes. Denver's defense has a bad tendency for getting beat deep on critical downs and Wilson can exploit that with his scrambling ability to buy time.

Wilson has been under duress on 38.8 percent of his third-down plays and converted for a first down only 18.8 percent of the time when pressured. Denver has put the quarterback under duress on 24.2 percent of third downs, allowing a conversion on 20 percent of the pressures.

The defense that does a better job of getting to the quarterback will likely win this game. For as good as Seattle's defense has been, Manning has too many options to go to. He'll find the right one given enough time. Wilson's magic acts in the backfield can be feast or famine, but he's going to strike deep and Denver can only hope someone in the battered secondary will be there this time around. If Denver can eliminate those miscues, the Broncos may actually have the advantage.

Note: Statistics used for this article compiled from Football Outsiders game charting, ESPN Stats & Information and Pro-Football-Reference.