How passing and rushing affect winning in the NFL

bill_belichickBefore the Super Bowl, Bill Belichick told his Giants defense to let Thurman Thomas rush for 100 yards.

As David Halberstam writes in Education of a Coach, it was a tough sell before the 1991 Super Bowl against Buffalo. The New York Giants played a physical defense that prided itself on not allowing 100 yard rushers.

No matter, the short, stout coach looked straight into the eyes of Lawrence Taylor and Pepper Johnson and said, “You guys have to believe me. If Thomas runs for a hundred yards, we win this game.”

Just in case his players didn’t listen, Belichick took it upon himself to ensure Thomas got his yards. He took out a defensive lineman and linebacker and replaced these large bodies with two defensive backs. In football lingo, the Giants played a 2-3-6 defense designed to struggle against the run.

Did Bill Belichick go insane? I certainly thought so when I first read this story years ago.

However, analytics is on Belichick’s side. Let me explain.

Visual shows the importance of passing over rushing

When it comes to winning in the NFL, passing is king. Rushing hardly matters.

To quantify this, our football obsessed culture must look past misleading statistics such as rush yards per game. Teams with the lead tend to run the ball to take time off the clock. Any team can rush for 100 yards if they run it 50 times.

To measure true skill, it is better to look at efficiency metrics like yards per attempt. A team can’t fake their way to 5 yards per carry by running the ball more.

Here, efficiency for passing and rushing is defined as yards gained per attempt on offense minus yards allowed per attempt on defense. Higher values indicate more team strength. Sacks count as pass attempts, and these negative yards lower pass efficiency on offense.

The visual shows the pass and rush efficiency during the regular season for all NFL playoff teams from 2003 through 2012.

nfl_pass_rush

From the left panel, playoff teams excel in passing, both throwing the ball on offense and preventing the pass on defense. Only 15 of 120 playoff teams in this era allowed more yards per pass attempt than they gained.

The visual also highlights teams that played in the Super Bowl. Eight of the ten Super Bowl champions were among the NFL’s elite in pass efficiency. However, excellence in the air does not guarantee playoff success. The New York Giants in 2007 and Baltimore in 2012 won the Super Bowl despite subpar pass efficiency.

Rushing hardly matters in the NFL

While the importance of passing in the NFL will not surprise anyone, the insignificance of rushing might. The visual for rush efficiency shows playoff teams as a random scatter of positive and negative values for their regular season statistics. A strong run game on offense and defense does not help a team make the playoffs.

Moreover, teams with a high rush efficiency do not suddenly become clutch in the playoffs. Almost half of the teams that played in the Super Bowl allowed more yards per carry than they gained. In 2006, Indianapolis won the Super Bowl while having the worst rush efficiency in the NFL. Green Bay in 2010 and the New York Giants in 2011 weren’t much better.

A guessing game of a team’s wins

Running the ball does not affect winning as much as you think. To illustrate this point, consider this guessing game. Suppose you want to guess how many games a team will win during the regular season. Without any other data, it makes sense to guess 8, the average number of wins in a 16 game season.

From 2003 through 2012, this estimate would be wrong by 3.1 wins. In technical jargon, 3.1 is the standard deviation of actual wins from the guess of 8. In normal people language, it says 2 of 3 teams will be within 3.1 wins of the guess. About two thirds of NFL teams won between 5 and 11 games between 2003 and 2012.

With the rush efficiency for each team, how much better does your guess get? The right panel of the visual below shows how rush efficiency relates to wins for every NFL team from 2003 through 2012. Simple linear regression gives the best fit line through the data.

nfl_pass_rush_scatter

The regression line gives a new guess about the number of games a team will win. For example, suppose a team has a rush efficiency of 0.6 yards per carry. Instead of guessing 8 wins for this team, the line gives 8.7 wins for this team.

How much better are these new guesses? Not much. The error only drops from 3.1 wins to 3.03 wins. In technical jargon, rush efficiency explains only 4.4% of the variance in wins. You might as well guess randomly.

The results get better using pass efficiency, as shown in the left panel. The error in estimating wins drops from 3.1 to 1.96. Pass efficiency explains 62% of the variance in wins in the NFL. The strong relationship is clear from the visual.

In college football, rush efficiency correlates more strongly with wins than in the NFL. Teams like Alabama, Stanford and Wisconsin have won with a power running game and a physical front seven on defense. The insignificance of running the ball is unique to the NFL.

Analytics gives a broad view of how passing and rushing affect winning. But to dig deeper, let’s look at specific teams and their strengths in these areas.

Indianapolis Colts

Under the leadership of GM Bill Polian and QB Peyton Manning, the Colts had a remarkable run from 2003 through 2010. They won at least 12 games each year before slacking off with 10 wins in 2010.

They achieved success through the air, ranking in the top 8 in pass efficiency each year. Peyton Manning and his offense played the bigger role, but the pass defense helped out some years. The Colts ranked in the top 10 in pass defense (yards allowed per attempt) from 2007 through 2009.

However, Indianapolis was really bad in the run game. Only once in this era (2007) did they gain more yards per carry than they allowed. As mentioned before, they were dead last in the NFL in rush efficiency in 2006 when they beat Chicago in the Super Bowl.

New England Patriots

New England won 125 games, 2 Super Bowls and played in 2 others during the 10 seasons covered by the visual. They followed the same script as Indianapolis: strong in passing, weak in rushing.

From 2003 through 2012, New England ranked in the top 10 in pass efficiency in each year except 2008 and 2012. In 2008, QB Tom Brady got hurt in the first game of the season. New England ended the season 13th in yards gained per pass attempt and did not make the playoffs, the only time this happened during these 10 years.

However, New England has never cracked the top 10 in rush efficiency. Coach Bill Belichick might not have seen the data presented here, but he gets the futility of rushing in the NFL. This understanding extends as far back as his days as defensive coordinator for the Giants.

Indianapolis and New England have built their teams around passing at the expense of rushing. They, along with New Orleans of recent seasons, have had success in winning games and Super Bowls. Now let’s look at teams that excel at rushing.

Minnesota Vikings

More than any other team, the Vikings dominate the ground game. They feature RB Adrian Peterson on offense and have tackles Pat and Kevin Williams clogging up the middle on defense. For the 6 years between 2007 and 2012, Minnesota has finished 1st in rush efficiency 4 of those years.

However, this strength has led to ups and downs in wins. Minnesota went 3-13 in 2011 despite leading the NFL in rush efficiency. The next season, they led the NFL again behind a monster season from Peterson, who made a remarkable return from knee surgery. The Vikings had 10-6 record that season.

The Viking’s best season over this stretch came in 2009. They finished 12th in rush efficiency that season. The difference? A QB named Brett Farve came out of retirement to play for Minnesota. The Vikings finished 7th in yards gained per pass attempt. They went 12-4 and came within a late turnover against New Orleans of playing in the Super Bowl.

San Francisco

The Niners started winning games when coach Jim Harbaugh became coach in 2011. However, they had their strengths before he arrived. Behind DE Justin Smith and LB Patrick Willis, San Francisco had an elite run defense. From 2007 through 2012, they never finished worse than 8th in yards allowed per carry.

This run defense didn’t help them win much the first 4 seasons, as the Niners won only 26 games. The pass defense never finished better than 15th during this time.

When Harbaugh arrived in 2011, San Francisco drafted LB Aldon Smith, a pass rush monster out of Missouri. They also signed CB Carlos Rogers, who had the first Pro Bowl season of his career in 2011. The Niners have finished 9th and 3rd in pass defense in 2011 and 2012 respectively. This resulted in 24 wins during these two seasons.

How to evaluate NFL statistics

In Super Bowl XXV, Bill Belichick’s plan to let Thurman Thomas rush for 100 yards worked, maybe too well. Against a small defense designed to slow down the pass, Thomas ran for 135 yards on 15 carries, a staggering 9 yards per carry. In the second half, he broke off a 31 yard run for a touchdown.

The game ended when Bills kicker Scott Norwood sent a field goal attempt wide right. The Giants won the Super Bowl 20-19.

The Giants did not win the game solely because of Belichick’s defensive plan. The offense generated two long scoring drives in the second half that took time off the clock. And I would bet my life savings Belichick did not want his defense to allow that 31 yard touchdown run to Thomas.

But, as Halberstam discusses in Education of a Coach, Belichick did want the Bills to pick up small gains on the ground if it meant keeping Jim Kelly from throwing the ball. He understood that rushing means almost nothing to winning in the NFL.

If you’re going to remember anything from this article, it should be this: look at a team’s passing instead of rushing numbers to determine whether they will win games.

3 things numbers tell us about the Super Bowl

The New England Patriots will play the New York Giants in the Super Bowl this Sunday. The Power Rank offers some numbers based predictions on the outcome.

1. It is not 2008. As you might have heard, the Patriots and Giants played in the Super Bowl recently. On February 3, 2008, the Giants pulled off a 17-14 upset over Tom Brady, Randy Moss and the Patriots. While Peter King at SI.com sees many of the same characters this time, this doesn’t mean the teams are similar. The Power Rank gave the 2007 Patriots a 14.7 rating, meaning they were more than 2 touchdowns better than the average NFL team. No other NFL team this past decade has come within 2 points of that year end rating. Our methods predicted that New England would beat New York by 11.1 points in 2008. The Giants cashed in a 19% probability of winning that game. This year, New England has a 8.3 rating, and The Power Rank predicts a point spread of 3.1. The Giants have a 40% chance of pulling the upset.

2. New England’s pass defense really is bad. Many have noted New England’s inability to defend the pass this year. The Patriots ranked next to last in total pass yards given up in the regular season. However, even the best pass defense will give up yards if the opposition throws enough. A better measure of pass defense is yards per pass attempt. But the Patriots don’t look much better by this metric. New England gave up 7.1 yards per pass attempt, 29th out of 32 teams.

3. Expect a lot of points. We also use The Power Rank algorithm to rank offense and defense. These rankings amount to scoring offense and defense that account for strength of schedule. Including the playoffs, New England has scored 32.3 points per game, but we assign an offensive rating of 28.8, still 2nd best in the NFL. This lower rating suggests that New England faced poorer defenses this season. The rating also implies that New England would score 28.8 points against the average NFL defense. New York has scored 25.0 points per game but has a 25.2 offensive rating, 5th best in the NFL. The offense and defense rankings predict a 31.5-28.6 final score for the Super Bowl.

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Can a defense force turnovers? SI.com looks at the art of fumbles

Earlier this week, Chris Harry at SI.com wrote an article on the art of forcing fumbles. Defenders, such as Charles Tillman of the Chicago Bears, “have used running backs, wideouts and tight ends as their personal canvases to become Picassos when it comes to getting the football on the ground.” The article’s timing was impeccable after San Francisco’s Kyle Williams fumbled two punt returns in an overtime loss to the New York Giants in the NFC Championship game.

But numbers just don’t support the argument that a defense can force fumbles. Bill Barnwell at Grantland found a weak correlation between turnovers in the first 5 games and the last 11 games of an NFL season. (The study found a correlation coefficient r=0.14 over a sample of over 600 NFL teams over 21 years.) Harry actually offers us more evidence. He states that Tillman forced a career high 6 fumbles in 2009. Since the Bears faced 1033 plays that season, he had a forced fumble rate of 0.6%. Not a Picasso level of forcing fumbles in my mind.

Have any thoughts? Think that someone needs to do a player based analysis on forcing fumbles? Leave us a comment please.

Note: Sports Reference claims that Tillman forced 6 turnovers in 2009, with 2 interceptions and 4 forced fumbles. It’s not clear whether Chicago recovered any of those fumbles. And, of course, Tillman probably didn’t play in every play in 2009. And he wasn’t near the ball on every play. But the picture is clear: his forced fumble rate was low even in his best year.

For more content, find The Power Rank on Twitter.

Related Posts:

About The Power Rank.
College football rankings.
Can a defense force turnovers?
The Power Rank featured on KALX Spectrum, the science and technology show on UC Berkeley student radio.

NFL Rankings, Week 13

Week 13…  one month to go until the end of the season!

With five games left to play this season, things are certainly heating up but some teams are cooling down.

As mentioned last week, the Bears (#7, 4.24) struggled without Jay Cutler at the helm, and may be at the beginning of a skid with their offense in the very unsure looking hands of Caleb Hanie. Their defense and Matt Forte will keep them in games, but with Hanie looking like Rex Grossman minus the talent, turnovers may kill this team’s hopes of playing in January.

Lucky for the Bears the Lions (#10, 2.00) also lost a star player when Ndamukong Suh decided to curbstomp the Packers’ backup guard Evan Deitrich-Smith on Thursday.  After grabbing Deitrich-Smith’s head and smashing it into the turf a few times, Suh was pulled away from the guard by other players.  Suh was not quite finished and with clear intent stomped on Deitrich-Smith’s arm while the player was still on the ground.  Suh was immediately ejected in the loss, and for the brutality of the infraction as well as his apparent lack of remorse for the act (he later claimed to be trying to regain his balance, but has since admitted his mistake) he has been suspended for the next two games as well.

The Texans (#6, 5.48) are on a roll and with the Colts (#32, -12.10) finally out of their way the AFC South title seems to be in their grasp.  But two weeks ago Matt Schaub’s season ended with an injury, and last week his replacement Matt Leinart, who was playing well, also succumbed to a season ending injury.  Tyler Yates finished the game and is slated to start this week, but Yates is just not the guy to inspire confidence in a team as they come down the homestretch and into a playoff run.  Kellen Clemens has been brought in as a virtual 4th string quarterback in the event that Yates’ season also ends abruptly, but do not expect big things out of either player.  Even though the Texans have thrived on solid defense and a dynamic running game, Yates invites opponents to stack the box against the run and put Houston to the test.  With only a two game lead over Tennessee (#13, 0.86) the Texans might be headed for more heartbreak than glory.

Oakland (#14, 0.30) is playing well and looked good driving the ball against Chicago’s stout defense last weekend.  Unfortunately for them, the Tim Tebow tide is taking over.  The Broncos (#18, -1.25) are nipping at the heels of the Raiders in terms of The Power Rank, and after a four game win streak are only one game behind the division leader, and are only one game out of the second wild card spot as well.  The real secret to Tebow’s success, unless you believe in divine intervention, is a combination of an emerging defensive powerhouse led by this year’s second-overall draft pick, Von Miller, and Tebow’s excellent ball security.  Denver’s defense has allowed Tebow’s anemic offense to win games in spite of averaging less than 20 points per game.  It’s not so much that Oakland is hurting…  in fact, they are doing fairly well under veteran replacement Carson Palmer.  It’s more that Denver seems to be getting hot at the right time.  If they keep their momentum going Oakland may take a back seat in the division and miss a shot at the playoffs.

Finally, the Giants (#17, -0.70) are starting to match their record with their mediocre rank on The Power Rank.  Our numbers have shown them to be overachievers all season long, and they have finally allowed slow starting Dallas take control of the NFC East with their recent three game losing streak.  With a probably loss at home against Green Bay (#1, 12.54) this weekend, the Giants will fall to 6-6, a mediocre .500 record that matches their inconsistent play this year.

Expect these downward trends to continue as the season winds down.

NFL Rankings, Week 8

This week I am going to take a page out of the Fox News playbook.

Hey?  Where are you going?  Don’t worry, I’m not going to try to sell you Food Insurance.  I just want to focus this week’s discussion on the key battleground divisions the way news networks look at swing states while ignoring the rest of the country.  So Rams fans can breathe easy, I won’t be taking so many shots at your team this week.  Besides, you should all still be celebrating the (baseball) Cardinals victory!

Battleground Division #1 – NFC North

The NFC North is stacked with talent this year, led by the Super Bowl champion and The Power Rank leader Green Bay Packers (#1, 11.55).  Normally having a team like the Packers in a division would settle matters, but this year it does not.  The reason is that the Lions (#4,  5.17) are right on the Packers’ heels, and the Bears (#9, 3.78) are not that far behind.  That’s three top ten teams in one division.  The Lions may have a hard time keeping up their pace especially with their oft-injured quarterback having ankle problems last week, and the Bears are legendary for pulling wins out of thin air.  Just ask Dennis Green!  Even if the Packers’ high level of success continues and they lock up the division title early, the Bears and Lions will both still likely be in the playoff hunt, in fact if the playoffs started today both teams would receive a wildcard berth.  With a lot of division games left the NFC North division is going to be an interesting one to watch.

Battleground #2 – AFC North

What’s with the North being so good at football?  Although the AFC North doesn’t feature three top ten teams as the NFC North does, it comes very close.  This division is led by the Baltimore Ravens (#3, 7.80) but they are actually a half-game behind the Steelers (#11, 2.58) and only a half game ahead of the Bengals (#12, 1.69).  Now, I know nobody talks about the “top twelve” of any lists, but it is nonetheless impressive that this tight grouping all falls within the top 12 teams in The Power Rank.  It’s hardly a revelation to NFL fans that the Steelers and Ravens are going to be battling for a division title, or that the loser is likely to grab a wildcard spot.  What is unlikely is the upstart Bengals sticking their noses into the mix.  With a third solid team to contend with the Steelers and Ravens will not be able to take anything for granted this season, and the fight for a playoff berth may get ugly in this division that is known for misconduct both on and off the field.

Battleground #3 – NFC East

The NFC East doesn’t carry nearly as many strong teams as the NFC and AFC North divisions do, but with some schedule oddities the team that The Power Rank picks as the clear division favorite is lagging behind in the actual standings.  The Cowboys (#8, 3.85) should be running away with this division in light of the fact that their closest competition should be the Eagles (#18, -0.89) who are also struggling to find wins.  Instead the Giants (#24, -3.29) are leading the division with a 4-2 record.  True, it’s early in the season.  And yes, we at The Power Rank do think that as things shake out the Cowboys’ record will start to match their apparent strength.  Even so, with poor starts from teams with high expectations and surprising starts from teams with low ones, everyone is in the mix here and every game is going to be an especially heated contest.

Non-Battleground – AFC East

The Power Rank is scheduled to get some East Coast bias with our next software upgrade.  If you want to hear how this is the only division that matters this year (or any other) tune into ESPN.  We apologize for the inconvenience.  Sure, the AFC East has a lot of strength in top ten teams New England (#2, 9.77) and New York (#7, 4.36) but in spite of what some sports news anchors would have you believe, this is not news.  The addition of the up and coming Bills (#16, 0.41) is shaking some fans’ confidence in the Patriots and Jets getting their perennial playoff spots, but The Power Rank thinks otherwise.  The Bills are indeed a good team right now but good is not enough in a division that has contained two top ten (and usually top five) teams for the last few years.  This division will get down and dirty where it normally does (in the playoffs) with the teams it normally sends (the Pats and Jets).  Until then, my attention will be elsewhere.