Pressure: Telling the Whole Story

| July 16, 2012

There are lies, damn lies and statistics.

I don’t think Mark Twain was talking about the NFL when we uttered those famous words, but he may as well have been.

NFL-land is populated by all sorts of numbers. Some of them interesting, some of them obvious, and some of them largely irrelevant. All of them, however, often used to promote one agenda or another.

The one that really gets me? It’s the abuse of the sack stat.  

 

The Sack Stat

How do you know a defensive lineman had a good year? Look at his sack numbers. How do you know an offensive lineman had a good year? Look at how many sack he gave up. It’s the simplest way to do things–after all, it’s near impossible to break down every game without having an entire team dedicated to doing so.

The only problem is those sack numbers are extremely limited.

The sack stat tells you that Jared Allen had 22; more than any other player in the league. But that number doesn’t tell you who they came against, or how many opportunities he had to rush the passer. The sack number doesn’t account for the quarterback who kept pressure from turning into sacks, and it doesn’t tell you at what point of a game they came.

See how limited it is?

Take a look at a player like Eugene Monroe, for example. He gave up nine sacks last year. Sticking in the AFC South, how about we compare that to, say, Michael Roos. The Titans’ left tackle gave up just one sack the entire year.

A slam dunk case of one tackle being better in pass protection than the other, right? Well, how about we look at some more numbers that compare the two.

 

Player
Team
Pass Block Snaps
Sacks
Hits
Hurries
Total Pressure
PBE
Time in Pocket
Eugene MonroeJAX44494122595.32.8
Michael RoosTEN61919253595.72.4

 

Suddenly things aren’t quite so clear-cut. In fact, while Roos walks out with a slightly better Pass Blocking Efficiency rating (a statistical way of measuring a player’s pass protection), it’s nowhere near what the sack numbers would suggest. What’s more, you can see a column at the end entitled ‘Time in Pocket’. This is the time from when the ball is snapped to when the quarterback has finished passing, taken a sack, or scrambled past the line of scrimmage. Roos, on average, had to pass protect for four-tenths of a second less than Monroe on every play.

This might not seem like a big deal until you consider that over the course of the season that means Monroe spent an extra 242.4 seconds in pass protection. Again, not a number that seems like a lot, but realizing the average pass play takes around 2.8 seconds, Monroe in essence had to face 86 extra passing situations because his quarterback held the ball longer.

It’s not an exact science, but you get my point: statistics in the NFL are not an exact science.

Defining the Lines with Sack Sums 

Still, when people fire away talk of the worst offensive lines, they look at those sack numbers. It’s why recently I’ve had someone explain to me that the Giants’ offensive line was better than the Cowboys’ offensive line because Tony Romo took more sacks than Eli Manning.

Wrong.

For a start, this doesn’t include sacks that are on the quarterback for holding the ball too long. We define ‘too long’ as being anything over four seconds, and in this regard Romo leads Manning 3-to-1. It also doesn’t account for sacks pegged to skill position players who have stayed in to help, where the Giants only gave up one sack compared to two for the Cowboys.

But more importantly it doesn’t account for the quarterback’s ability to get rid of the ball and avoid sacks. If you want to look at this in number form, we have a nice little figure that shows the amount of pressure each quarterback faces and the percentage of that which ends up in a sack. The Giants’ QB is down at 11.5% (lowest in the league), while the Cowboys’ passer is up at 20.6% (10th-highest in the NFL).

You see that’s the beauty of stats. You dig a little deeper and you find something that can expose the limitations of another. A perfectly executed cross examination, if you will.

The Impact of Pressure

See here’s the thing: sacks aren’t the be-all and end-all. If you think they are, you’re either confused, foolish, or someone who just doesn’t get football.

The idea of pass rushing is to get to the quarterback and influence him. Now, a sack is the ultimate form of influence as it results in a guaranteed negative play, but you better believe that hurrying a quarterback makes life a lot harder for a passer. For some numbers to back that up, have a look at the combined stats for the 35 quarterbacks who dropped back from center more than 200 times last year:

 

Situation
Att.
Comp.
Comp %
Yards
Y/A
TD
INT
TD:INT
Without Pressure11152732465.70%864407.755412731.98
With Pressure3895179146.00%233065.981331470.90

 

It doesn’t take a genius to figure out that pressure increases your chances of throwing picks while hindering your ability to complete passes and significantly reducing your yards-per-attempt average. It’s kind of the difference between having Tom Brady as your quarterback and Tim Tebow throwing the ball; only you don’t get any of the benefit of Tebow’s athleticism.

And people say pressure doesn’t really impact your quarterback.

It’s Just a Number

You know what the annoying thing is? If used correctly, the sack number is an important tool. It is often representative of the amount of pressure a player is getting, and as the ultimate play a pass rusher can make (the one guaranteeing a negative play for the offense), it is hugely important. But it’s a part of the puzzle, not the entire thing.

For pass rushers and pass protectors that means looking at all forms of pressure and then breaking down how quickly these pressures come. As analysts, that means looking at what times a pressure comes in a game and against whom it comes. We stand by our grading as being the best tool out there for identifying the best pass rushers and best pass protectors, after all it looks at how quickly a pressure comes, when it comes and how often it comes.

But even that, the most advanced measurement of play, shouldn’t be treated as gospel.

So, whenever you look at any numbers regarding sacks, pass rushing, or pass protection don’t just switch off. Look into them, because often times the face value won’t tell you the whole story. It’s how the team at PFF uses them and, if you really want to understand what’s going on, take off the blinders and do the same.

 

Follow Khaled on Twitter: @PFF_Khaled … and our main feed too: @ProFootbalFocus

  • qweasdzxcxz

    Great article. Now that you have will have access to the All-22 tape(thank god) and can see everything, will you change your definition of “holding the ball too long” to be dependent on the play? Like if there is clearly no option available for the first 4 seconds, and the QB scrambles and makes a play happen after 5 seconds.

  • Topher Doll

    Great article as always, thanks. Also, are you planning on adding Time in Pocket as a Signature Stat?

    • uppercut

      I would second this :) (THOUGH, I know that it takes time/thought to give the SS section the revamp it needs (like yards thrown for QBs-under-pressure, or routes run for WR/TE-in-slot, etc)

      and of course, great article!

      Oh! But, when you say Moore spend extra seconds in the pocket over a season – do you mean an “average season” where both OT blocked the same amount? (Because with Moore’s much fewer pass protecting snaps, he still would have been blocking fewer total seconds in the season than Roos).

  • nm98966n

    great article…been reading your articles for a few months now. I feel like all these “analysts” from sportscenter to blogs like bleacherreport can be so misinformed by the simple stats like passing yards, sacks, touchdowns, etc. You guys have single handedly proven why eli is the best qb in the nfc. Your stats should put the eli vs romo argument to bed.

  • nm98966n

    nfc east* lol

  • http://www.profootballfocus.com Khaled Elsayed

    Re: All-22 not entirely sure what you mean. I’d caution, personally, people getting carried away by All-22 because of when it will get released primarily.

    Re: Time in Pocket, it’s something we’re looking to add as it could help explain a fair few things. It’s certainly something we’re looking to make better use of as we only started recording it last year and didn’t really go in with a clear purpose of what we were hoping to gain from it.

    Re: Manning vs Romo … one of those contests where the eye test won’t let you down

    • uppercut

      Not sure if you’ll see this but – what I believe that poster meant (re: all-22), is that being able to see the whole field you could possibly see that all receivers are covered for 4+ seconds and it might “justify” the QB holding onto it for 4 or more seconds (currently your designation of “too long”).

      Although personally I would have already thought that the “answer” would be that even if they are covered he should already have thrown it away or started running then.

      • Neil Hornsby

        Our own Nate Jahnke did some internal work on this for us recently and the truth is, after 3.9 seconds the average “result” of the passing play drops off markedly. If a QB holds onto the ball for 4+ seconds, bad things tend to happen.

        • ivanross

          I would “third” the notion of time in the pocket as a key stat I think you could hang a whole bunch of interesting analysis off.

          My “eye test” suggests this stat is THE key difference between Manning & Romo. Manning has the ability to extend the play when the situation calls for it but more enough than not, throws the ball away. Romo NEVER throws the ball away – and while he is often lauded for his ability to extend the play, I suspect as you suggest a lot more bad things than good things happened in those situations.

  • kevnh52

    Someone needs to check the math on the time in the pocket analysis. According to the numbers listed, Roos actually spent 242.4 seconds more in the pocket. Not the other way around. Math: Roos (619 c 2.4 = 1485.60) Monroe (444 x 2.8 = 1243.20) 1485.60 (Roos) – 1243.20 (Monroe) = 242.40. Does this mean instead of being more equal, Roos is really much better?

    • kevnh52

      Also, isn’t saying “Monroe in essence had to face 86 extra passing situations” a bit of a stretch since Roos actually took 175 more real snaps?

      • http://www.profootballfocus.com Khaled Elsayed

        He spent more time in the pocket because he faced more snaps. I was looking at the average time each man faced, and then zeroing in on Monroe’s numbers to say that even though he comes out as less efficient etc, that if you consider the extra time he spent in the pocket then he gave up less pressure per time in the pocket. Monroe gave up 25 pressures in 1243.2 seconds protecting (a pressure every 49.7 seconds) while Roos gave up 35 pressures in 1485.6 seconds (a pressure for every 42.4 seconds he was in pass protection).

  • kevnh52

    Thanks for the explanation. That seems like a much better way to put it than the seemingly random “86 extra passing situations”. I still think the 175 actual snaps is far more important. I’d be curious to see what Roos’ numbers and averages looked like after his 444th pass play.

    I do appreciate the impossibility of standardizing NFL statistics; especially one as nuanced as pass blocking. I think you’re onto something with the pressure every X seconds.

    Also, please keep talking about the interior linemen (both offensive and defensive). There is not nearly enough coverage of, arguably, the most important parts of any football team.