Super Bowl LI Preview: An Analytical Guide to Sunday's Big Game

We're not always this lucky.

The best teams in football aren't always in the Super Bowl. Sometimes one conference is stacked, leaving us with an overwhelmingly heavy favorite on one side of the ball. Sometimes a team gets hot at the right time and makes a run for the title.

Sometimes we get Rex Grossman.

This year, we've got a battle, man. The New England Patriots are our top-ranked team -- one that was clearly the best in the AFC this year. Meanwhile, the Atlanta Falcons rank second-best according to our metrics.

And the gap between these two teams and the rest of the league is -- or was -- massive.

So who's going to be lifting the Lombardi trophy on Sunday? If it's New England, how are they going to stop the Falcons' high-powered offense? If Atlanta, how can they beat the all-around better team?

Let's dig in.

A High-Level Look

Plain and simple, our numbers have given the Patriots the edge over the Falcons all season long. And by "numbers", I'm referring to our all-encompassing nERD metric, which measures the number of points we'd expect a team to win by against an average squad on a neutral field.

To put this another way, a team with a nERD of zero is completely average. A team with a nERD of, say, -3.28 would be expected to lose to an average team by a little over a field goal.

Here's how New England and Atlanta have looked week by week according to nERD this year.

Back in Week 12, both teams had a nERD of 5.65 -- that came after New England squeaked one out against the Jets while Atlanta crushed the Cardinals. Other than that instance, the Patriots have been better -- and sometimes much better -- than the Falcons.

However, there's no doubt that Atlanta's seen the bigger rise all year. Back before the season started, they were listed as a below-average team. After a Week 1 loss to the Buccaneers, they were a bottom-of-the-barrel one.

And then Matt Ryan happened.

A Quarterback Battle

The biggest storyline surrounding Super Bowl LI has to be the quarterback matchup. On one side of the field, you've got the guy who's done this six freaking times. On the other, you've got the likely league MVP -- someone looking to finally get the monkey off of his back.

According to our Net Expected Points (NEP) metric -- which you can read more about in our glossary if you're new to the site -- Brady and Ryan were the two best quarterbacks in the NFL this year during the regular season.

To give you some historical context, the difference between Ryan's per drop back rate this year to the league average is roughly the same as what we saw from Kurt Warner to the NFL mean back in 2001. And, clearly, given Brady's efficiency is close, he's not far off, either.

Both quarterbacks will be tough to stop, and it'd be shocking if they were halted completely. But there are ways to slow them down.

Limiting Yards After the Catch

One of the ways Matt Ryan was able to collect such gaudy numbers this year was through the big play.

Fortunately for the Patriots, they've been strong against big-armed tosses all season long.

Take a look at the chart below that depicts the number of 20-, 25-, 30-, 35-, and 40-plus yard plays accumulated through the air by the Falcons this year, as well as how many of those types of plays were allowed by the Patriots. The gray bars represent the league average per team.

Essentially, what this is showing us is that the Falcons have been able to crush defenses with home-run plays, while the Patriots have been really good at defending the deep ball. In fact, no team had more 40-plus yard passing plays in 2016 than Atlanta, while only the Denver Broncos were better at preventing those types of plays than the Patriots.

This aligns with what numberFire's Jim Sannes wrote about just last week. In his article, he discovered that Matt Ryan was more than twice as efficient -- per NEP -- on throws 16 or more yards down the field this year versus a league-average quarterback. At the same time, the Patriots were almost twice as good at defending those types of passes compared to the league's average defense.

But here's the thing: a huge reason Atlanta was able to complete so many big plays this year wasn't just because of Matt Ryan's big arm. It was because his pass-catchers did a lot of work after the catch.

On the season, 51.90% of Ryan's yards came via the air, while the remaining 48.10% came after the catch. Among the 30 quarterbacks with 2,000 or more yards this year, Ryan's air yards percentage ranked 19th.

The other side of the ball features a Patriots' defense that allowed just 91.44 yards after the catch per game, which was the absolute best average in the NFL this season.

And among the five teams Atlanta lost to this year -- Tampa Bay, Seattle, San Diego, Kansas City, and Philadelphia -- only the Chargers ranked outside the top-15 in yards after catch allowed per game. Moreover, in those losses, the Falcons averaged 1.8 passing plays of 25-plus yards per contest, while they averaged 3.0 in their 11 regular season wins.

The big play is key for Atlanta's offense, and this might be the defense that can contain it.

Getting to Brady

Entering this year's AFC Championship, there was a lot of talk around the new and improved Pittsburgh pass rush. For good reason, too: when Pittsburgh was 4-5 after their heartbreaking loss to Dallas in Week 10, their sack rate was just 3.71% -- they were tackling quarterbacks behind the line of scrimmage on just 3.71% of drop backs faced. That was second-worst in the NFL at the time. After that Cowboys game, the Steelers drove their sack rate to 8.76%, which was the second-best rate in football during the second half of the season and into the playoffs.

Much of that had to do with an increase in blitz rate. Per Pro Football Focus' Pat Thorman, Pittsburgh upped their rate of blitzing from 26% before their Week 8 bye to 43% after it. They went from being not-so-blitz-heavy to a fairly-blitz-heavy team.

Tom Brady picked them apart in the AFC Championship.

Say it with me: you can't beat Tom Brady by blitzing him. You have to beat Tom Brady by pressuring him.

The Steelers weren't their blitzing selves in the conference championship, but they weren't able to generate natural pressure on Brady, which is why he was able to do what he did against them. Without pressure this season, Brady threw 21 touchdowns without a pick to go along with a 123.02 quarterback rating.

Unfortunately for the Falcons, they run a fairly similar Cover 3 defense as Pittsburgh does. The biggest difference is that they weren't nearly as blitz-friendly during the regular season, sending players on just 20% of their defensive snaps (thanks again to Thorman for that nugget), the third-lowest in football. They also had a low sack rate as a result (5.07%, 25th-ranked one in the league).

But they did start playing more man-to-man coverage as the season progressed, which should help in this particular matchup -- the Steelers failed to make those types of adjustments in the AFC Championship, which is a big reason they failed to win.

The bottom line here, though, is that Atlanta will need to pressure Brady without the blitz. This is no different than what the Giants used to do against New England when they matched up in the Super Bowl over the last decade, and why New York was consistently victorious.

A Secondary to Exploit

If the Falcons can't get organic pressure on Brady, it could be a long day for their secondary, which is one that comes into the Super Bowl ranked in the bottom-10 according to our metrics.

How can Brady and company pick them apart? Let's start by taking a look at the following chart, courtesy of NFL.com's Matt Harmon.

If you're a big fantasy football nerd, you may be aware that the Falcons gave up a ton of fantasy points to opposing slot receivers this season. While that clearly has something to do with a weak defense, it also has to do with volume: the Falcons faced 691 passing plays this year, which was easily the most in the NFL.

The chart above shows an obvious area of the field to target, which is the deep left side. That'll more than likely be Chris Hogan territory, so don't be surprised if they take a shot or two with him down the field.

Where things might be most intriguing is behind the line of scrimmage and out of the backfield. In 2016, no team allowed more running back receptions than Atlanta. Sure, much of that can be tied to what was just said about volume, but it also matches up with how poorly they defended that area of the field.

During the regular season, New England targeted their running backs on 24.07% of the team's attempts, good for the fourth-highest rate in the NFL. Meaning, aside from the standard areas of the field where the Falcons' D can be exploited, perhaps this becomes a game where Dion Lewis and James White are featured more than usual as receivers.

Running Backs for the Win

It's not like the Patriots have the edge in the running back department, though. New England actually surrendered the second-most receptions to running backs this year, and Atlanta targeted their backs on 22.08% of attempts during the regular season, which was sixth-most in the NFL.

And Devonta Freeman and Tevin Coleman -- specifically Freeman -- are probably more important to this Super Bowl than the trio of backs in New England (which also includes LeGarrette Blount). Actually, they definitely are.

New England gets praise for their rush defense, as they allowed the second-fewest rushing yards per game this season. They also faced the third-fewest rushing plays -- again, volume matters for cumulative statistics.

According to our schedule-adjusted numbers, the Patriots rush defense is good, but not elite, ranking eighth-best in the NFL. It's basically just as strong as the team's pass defense, per NEP.

Freeman will be one of the toughest running back matchups the Patriots have faced this year, too. The chart below shows that.

The x-axis above depicts Rushing NEP per rush averages, and the y-axis shows a player's Success Rate, or the percentage of runs that result in positive expected points. In other words, the top right portion of the chart is where the hyper-efficient, hyper-consistent running backs are.

Freeman is right there.

He's no Mike Gillislee, who's the big outlier among this group of runners that had 100 or more rushes this year but, per our numbers, Freeman was a top-five running back this season.

And where he'll probably play his biggest role in Super Bowl LI is on early downs, specifically first. During the regular season, Freeman averaged 5.40 yards per attempt on first down, ranking 8th-best among the 47 backs with 50 or more carries this season. The Patriots surrendered 3.80 yards per carry on first down this year, which was 10th-best in football.

The battle on early downs will be crucial for the Falcons in setting up sustainable drives, as well as the big play mentioned earlier. And Freeman is the guy who'll carry that load for them.

And the Winner Is...

Of course, there are a ton of other interesting matchups to watch during Sunday's game: Will the Falcons force Julio Jones to the slot? Will the Patriots try to use Malcolm Butler in shadow coverage? Can the Patriots interior lineman keep Brady upright?

The bottom line for the Falcons is that they need to set up their big passing plays by using their early-down ground game and, on defense, they've got to get to Brady without blitzing. The defensive line will be crucial.

For New England, it's all about doing what they've done all season long. In truth, they match up pretty well against Atlanta -- they limit big plays, they can utilize their backs out of the backfield, and they can generally stop the run well.

On paper -- and according to our math -- New England looks to be the team that'll lift the Lombardi on Sunday. But it's going to be close: we're giving them just a 54.30% chance to win.