Category Archives: New England Patriots

Why The NFL Can’t Rely On Defense

In an NFL season marked by historic offensive production and a championship round that was conspicuously absent a top-10 defense,2 aficionados of low-scoring rock fights, filled with punts and field goals, have been left disappointed. The best defensive teams to make the playoffs were eliminated early in the tournament, with the Bears, Ravens and Texans all losing in the wild-card round. A week later, Joey Bosa and the emerging Chargers defense were dismantled by the Patriots, and the Cowboys — perhaps the best defensive team left in the divisional round based on their end-of-season play — lost to the Rams. Extracting the strong defensive teams with relatively weak offenses led to historically exciting playoff football, producing two overtime games in the championship round for the first time in NFL history. Now we have a Patriots and Rams Super Bowl pitting perhaps the greatest QB of all time in Tom Brady against the hottest young offensive mind in the league in Sean McVay.
We shouldn’t be surprised that great offensive teams have made it this far. Teams are more reliably good — and bad — from game to game and year to year on offense than on defense. Individual defenders often have wild swings in performance from season to season, and defensive units forecast to be dominant often end up being merely average. The Jacksonville Jaguars’ defense took them as far as the AFC championship a year ago, but that same defense led them to five wins this season. Meanwhile, performance on offense is generally easier to forecast, making investments on that side of the ball more reliable.
Even then, football is largely unpredictable. When an otherwise sure-handed Alshon Jeffery3 lets a well-thrown Nick Foles pass sail through his fingers for an interception to end the Eagles season, or when Cody Parkey double-doinks a partially blocked field goal to end the Bears’ playoff hopes, we are essentially cheering, or bemoaning, randomness. Most vexing for forecasters and league observers trying to make sense of things is that the plays that matter the most in football are often the most unpredictable. But again, this is particularly true on the defensive side of the ball.
Turnover margin is the canonical example. Teams that win the turnover battle go on to win their games at a very high rate. Home teams win about 73 percent of their games when they are plus-1 in turnover differential, according to data from ESPN’s Stats & Information Group, and the home team win rate climbs to more than 86 percent when it’s plus-2 or better.

Yet despite their clear importance, the number of turnovers a team creates in one season has no bearing on how many turnovers the team will create in the next. Both interceptions and fumbles are completely unpredictable from season to season at the team level. And this pattern holds true for defense in general. If we measure the stability of defensive stats from one year to the next,4 we find that compared with offensive performance, most defensive stats are highly variable from year to year.

Defensive performance is unpredictable
Share of performance across various team-level metrics predicted by the previous season’s performance in the regular season, 2009-2018

metric
Share predicted

Total offensive DVOA
18.9%

Offensive passing DVOA
18.8

Defensive passing DVOA
10.0

Offensive rushing DVOA
9.7

Total defensive DVOA
9.7

Defensive rushing DVOA
8.3

Sacks
3.6

Interceptions
2.4

Fumbles
1.6

Source: Football Outsiders

High-impact plays on defense turn out to be the least predictable. And while we’re by no means great at identifying which teams will succeed on offense, offensive DVOA is about twice as good at forecasting future performance as defensive DVOA.5
For teams like the Chicago Bears, who won 12 games despite fielding the 20th best offense in the NFL, this has major ramifications. The Bears were third in the league in turnover margin and third in sacks — feats we shouldn’t expect to repeat based solely on this season’s results. (Just ask the Jags.) Casting even more doubt on their ability to field an elite defense in back-to-back years, Chicago also lost its defensive coordinator, Vic Fangio, who left to become the head coach in Denver, further destabilizing the strength of the team.
Still there is some hope for lovers of the three-and-out. While rare, there are plays a defense makes that do tend to carry over from year to year. One of the most stable defensive stats is hits on the quarterback, which has a relatively impressive year-to-year r-squared of 0.21 — better even than total offensive DVOA, which is the gold standard for stability in team metrics. Quarterback hits include sacks — 43.5 percent of QB hits end in a sack, and those by themselves tend to not be predictive — but also plays in which the passer is contacted after the pass is thrown, and that contact is incredibly disruptive to a passing offense.

When a quarterback is hit, his completion percentage is affected on a throw to any part of the field.6 Teams that can generate pressure that ends with contact on the opposing QB greatly improve their chances of causing incompletions and getting off the field. And best of all, teams that are good at generating hits on the quarterback tend to stay good at it.

Philadelphia led the league in QB hits but not sacks
Total quarterback hits, sacks and expected sacks for teams’ defensive lines in the regular season, 2018

Team
qb hits
Sacks
expected sacks
Difference

Philadelphia
123
44
53.5
-9.5

Pittsburgh
110
52
47.9
+4.1

N.Y. Jets
109
39
47.4
-8.4

Seattle
105
43
45.7
-2.7

Kansas City
101
52
43.9
+8.1

L.A. Rams
99
41
43.1
-2.1

Baltimore
96
43
41.8
+1.2

Chicago
95
49
41.3
+7.7

New Orleans
95
49
41.3
+7.7

New England
93
30
40.5
-10.5

Dallas
92
39
40.0
-1.0

Washington
91
46
39.6
+6.4

Jacksonville
90
37
39.1
-2.1

Tampa Bay
88
38
38.3
-0.3

Denver
86
44
37.4
+6.6

Houston
86
43
37.4
+5.6

Minnesota
86
49
37.4
+11.6

San Francisco
85
37
37.0
+0.0

Arizona
83
49
36.1
+12.9

Buffalo
83
36
36.1
-0.1

Cleveland
83
37
36.1
+0.9

N.Y. Giants
81
30
35.2
-5.2

Cincinnati
80
34
34.8
-0.8

Tennessee
80
39
34.8
+4.2

L.A. Chargers
77
38
33.5
+4.5

Detroit
74
43
32.2
+10.8

Indianapolis
74
38
32.2
+5.8

Atlanta
73
37
31.8
+5.2

Miami
73
31
31.8
-0.8

Green Bay
71
43
30.9
+12.1

Carolina
68
35
29.6
+5.4

Oakland
48
13
20.9
-7.9

Show more rows

Sources: NFL, Elias Sports Bureau

The Eagles, Jets and the Seahawks all appear to have better days ahead of them on defense. Each team racked up more than 100 QB hits in 2018. But they also experienced bad fortune, converting their hits into sacks at a rate below what we’d expect. If these teams generate similar pressure next season, we shouldn’t be surprised to see their sack totals rise just based on reversion to the mean. Meanwhile, Chicago, New Orleans and Kansas City experienced good fortune in 2018, converting their QB hits at a rate higher than we’d expect. Assuming the defensive lines return largely intact, we probably shouldn’t be surprised to see their sack totals dip next season.
Stats like QB hits are rare to find on defense. And because of the high variance in defensive performance, teams built with a defense-first mindset end up controlling their own destinies less than we might expect. When it comes to team-building, this suggests that investments on offense are better long-term bets for stability. The results this year are particularly encouraging. Lighting up scoreboards by focusing on scoring points instead of preventing them has proved to be both successful and incredibly entertaining to watch. For this season at least, defense isn’t winning anyone a championship.
Check out our latest NFL predictions.


Move Over, Brady. The Patriots’ Running Backs Are Stealing The Show.

The identity of the New England Patriots has been not having an identity. What’s made them so difficult to beat in the Tom Brady era is an amorphous quality that has them adapting a game plan effortlessly to any opponent. So the team’s emphasis on the run versus the pass — and to whom the passes are targeted — historically has changed based on where the defense of that week’s opponent is most vulnerable.
But the Patriots’ identity this season has seemed to take on a more specific shape — particularly in the postseason. Over the past two wins, the Patriots have become a power-running, ball-control passing team that has their offense flow through their backs. And even more shockingly, they often indicate whether they are going to run or pass based on who they have on the field. They are winning less with deception, instead simply daring the defense to stop them.
This postseason, nearly 59.9 percent of New England’s offensive snaps have ended with the ball in the hands of a running back (meaning a run or a completed pass to a running back), according to ESPN’s Stats & Information Group. Since 2001, this is the fourth-highest running back usage rate among playoff teams.

New England’s running back usage rate was 12 percentage points lower during the regular season — though its share of 47.5 percent was still the sixth-highest in the NFL. Rather than dialing down their running back usage and putting the season in the hands of the NFL’s greatest quarterback, the Patriots have dialed the RB game up to 11. This increase in running back usage is the highest in the 16 postseasons of the Brady-Bill Belichick era. Belichick and his coaching staff have typically chosen to go in the other direction — in 12 of those postseason appearances, the rate of running back touches went down. That includes last season, when it declined from 49.5 percent during the regular season to just 38 percent in their playoff run, which ended with a pass-happy Super Bowl shootout loss to the Eagles.
And not only can the defense reasonably guess that the ball is going to a running back, it can determine with an even higher degree of certainty whether Brady is going to hand off or pass depending on which running back is in the huddle.
In the regular season, when Sony Michel was on the field, the Patriots ran the ball 75.9 percent of the time. But when the Patriots subbed in James White, the Pats ran on only 23.8 percent of plays, while the Pats threw the ball the other 76.2 percent of the time. In the postseason, rather than seeking to cross up the opponent, their tendencies have somehow gotten even more extreme: 83.8 percent of plays with Michel on the field have been runs, while 89.2 percent of snaps with White have been throws. In the process, the Pats scored 78 points in their two wins and rolled up 1,022 yards, well above their per-game regular-season averages of 27.3 points (fourth most) and 393.4 yards (fifth). So, the game plan may be predictable, but it’s working.
(When necessary, the Patriots do have a back that they can deploy without strongly indicating run or pass. With Rex Burkhead on the field, the Patriots threw the ball on 53.2 percent of plays during the regular season. And in the postseason, that’s risen to just 55 percent.)
The Patriots have long championed passing to a running back, given that they drafted White in the fourth round in 2014 and quickly made him a receiving specialist with more career catches than rushes. But this heavy reliance on the run is a new identity for them. As recently as the 2015 season, their rate of running back usage in the postseason was just 24.1 percent, which ranked above only the 2011 Lions among all 216 playoff teams in the sample. Last year’s team ranked 158th in postseason running back usage. And their Super Bowl-winning edition in 2016 was 132nd. The last time a Brady-led Patriots playoff team was this running back-centric was in 2004, when the team had Corey Dillon and Kevin Faulk. With 54 percent (21st) running-back usage, that team beat the Eagles in Super Bowl XXXIX.
It’s unknown whether this transformation was by necessity or design. There’s no doubt that the passing game is without its full arsenal. No one expected a healthy Rob Gronkowski to virtually disappear as a receiving threat (149 yards in his past five games, though 79 came in the AFC championship). And the tight end’s ineffectiveness comes after former All-Pro wideout Josh Gordon in December first “stepped away” and then was suspended indefinitely from football for violating the terms of his reinstatement after he was previously suspended under the NFL substance-abuse policy.
So bereft of game-breaking receiving threats, the backs via Michel’s running and White’s pass-catching have had to fill the void in a passing game that was left in “shambles.”
Brady, for his part, has really ramped up his checkdown game. During the regular season, the Pats connected on just 74.8 percent of passes to backs (mainly White) within 5 yards of the line of scrimmage, which ranked the Patriots 28th in the NFL. New England’s success rate11 on these plays was just 49.7 percent, barely above the NFL average of 45.9 percent. But in the postseason, those numbers have climbed to a 85.2 percent on 27 passes to backs, including seven first downs, and a playoff-leading play success rate of 63 percent.
Even though running their offense through their backs was a trademark of New England’s regular-season success, we can’t dismiss the possibility that it just perfectly aligned with the weaknesses of its playoff opponents. The Patriots’ divisional-round foe, the Chargers, were reasonably stout against the run (12th in yards allowed per rush); but they had transitioned to a defense featuring smaller defensive backs in place of linebackers. And they were just 24th in the regular season on defensive play success on passes to running backs. The Chiefs were poor both against the run (31st in yards allowed per rush) and in preventing success on running back passes (31st).
The Rams are a mixed bag, actually ranking last in yards allowed per rush but first in preventing success on tosses to backs. That could end up meaning a lot more Michel and a lot less White in the Super Bowl. Or, given the Patriots history, this could all be an elaborate con — and Brady may cross up Los Angeles completely by throwing early and often to Gronkowski and his wide receivers.
Check out our latest NFL predictions.