Monday, December 31, 2012

Should JJ Watt win the MVP award?

by Joe Harris

DPOY? Hands Down…

Followers of ANS are probably likely to agree with the notion that JJ Watt is the run-away DPOY for this season, a large proportion of the mainstream media agree, and there is also a very good chance that he will, in fact, win. His main competitors were Aldon Smith and Von Miller who were both originally competing with Watt for the sacks title, but eventually lost out.
The ‘conventional’ stats bear out the idea of JJ Watt as the DPOY:
Stat
JJ Watt (Hou)
Aldon Smith (SF)
Von Miller (Den)
Sacks
20.5
1st
19.5
2nd
18.5
3rd
Tackles
69
50

55

Passes Defended
16
10th
1



2

Interceptions
0

1

1

Fumbles Forced
4
10th
3
22nd
6
3rd
Yards per Pass Attempt (Team)
6.7
7th
6.1
2nd
6.4
5th
Yards per Rush Attempt (Team)
4.0
9th
3.7
3rd
3.6
2nd
* The rank for each player was left blank if they did not come in the top 40 players
This shows Watt as a viable contender for DPOY, leading the other two in sacks, tackles and passes defended (where he ranks a ridiculous 10th among all defensive players). However, it is not quite clear cut as the other two both lead slightly better defences and Von Miller has more FF and an interception.
Personally, I think the above table shows Watt as the clear winner when put into the context that he is a DE in a 3-4 scheme whereas the other two are both LBs in schemes designed to give them opportunities to rack up the glamor stats.
The result starts to become clearer cut when we look at the Advanced Stats:
Stat
JJ Watt (Hou)
Aldon Smith (SF)
Von Miller (Den)
% adv
+WPA
2.96
1st
1.04

1.53
22nd
25%
+EPA
122.1
1st
58.5
12th
74.2
2nd
65%
Success Count
109
1st
60

65
32nd
4%
Tackle Factor
1.36
13th
0.67

0.71

-13%
QB Hits
43
1st
24
4th
27
5th
34%
Defensive GWP (Team)

9th

2nd

1st
-
* The rank for each player was left blank if they did not come in the top 40 players
Here Watt completely blows away his competition. I also added a final column which shows Watt’s advantage over the second place in each category. For example, he has 65% more +EPA than the next player (who happens to be Von Miller). That’s insane.  

Thursday, December 27, 2012

Wins above average: a statistical nightmare

by Clark Heins

Introduction: Davis Wylie (pen name of researcher Neil Paine), after much complicated math resulting in each QB‘s stats being “adjusted“ to 2006 levels (through a process known as “translation“, i.e., normalization without standard deviation, converted everything into a final stat “Wins Above Replacement Player” totals in his "The 100 Greatest QBs of the Modern Era” opus which he used to rank QBs.

In football, there is no clearly established formula for determining WAR figures, but Football Outsiders originally estimated that a “Replacement Level” QB was some 13.7% less effective (valuable) than an “average” QB. This percentage was later changed to 13.3% and now rests at 12.5%. All these figures were arbitrary and consisted of some educated guesswork and “value judgments” about “players“ who never existed! It would have been much easier if Wylie had simply used the stat “Wins Above Average” which we can all understand instead of an incomprehensible abstract.

The problem for me was converting these WAR totals to WAA so as to compare with Doug Drinen’s figures in his own WAA opus.

Thursday, December 20, 2012

Kelly Criterion on 4th down

by Tunesmith
It's 4th and 1 from your opponent's 43-yard line. You're up 3 points, and there is 5:16 remaining in the 1st quarter. Should you go for it?

According to the 4th Down Calculator, the answer appears clear. Based on history, there is an estimated 74% chance of converting a 4th down in that scenario. Success yields 0.68 WPA; punting yields 0.61 WPA, and failure yields 0.55 WPA.

These odds tell you that on average, it is a good decision to go for it - just the same as on average you'll make money if you take a bet with those odds and that probability of winning. The "Expected Value" (EV) in this scenario is 3.62. This means that on average, you will gain .0362 WPA by going for it.

However, average doesn't always cut it. Because if it's not certain, you could still lose.

EV enthusiasts often object to that observation, but let's briefly consider an alternate scenario. Pretend that you come across a certain state lottery. For $1, you have a chance of winning $500,000,000 profit. And your chances of winning are 1 in 350,000,000. (Also pretend, for the sake of argument, that there's a new identical lottery every second, and there can't be multiple winners in a round.) Since 500 > 350, those are good odds. Say you can play only once. Should you buy a ticket? What if you could play multiple times, or buy multiple tickets? Should you spend your $5,000 in hard-earned savings on lottery tickets?

Tuesday, December 11, 2012

1st Down Game Theory: Equilibrium and Exploitable Strategies

by Mike Sommers

You are faced with a first and 10 on your own 20 yardline, what percentage of the time should you run vs pass? You are on the 40 yardline, what percentage do you run vs pass?

Equilibrium Strategy
This is a problem that is solvable, but it depends upon your objectives. I used average NFL data. The average pass attempt yields about 11.6 yards per catch with a 60.5% completion rate. I rounded this down to 11 yards and 60% completion rate. The average rush attempt yields 4.36 yards (2011 data) I rounded this down to 4 yards. Now if you approach the problem as an “equilibrium” strategy, your goal is actually to reduce the expected effect on the play to no change in score either way. For those familiar with “EP” (expected points), this doesn’t mean that the EP result would be zero, but that over the long run, the EP would not increase or decrease from it’s current levels. That is, no change in expectation of how many points you score, so if your expected points on first and 10 is .34, using an equilibrium strategy, it will remain .34. This is based upon the assumption that in the very long run, the opponents will either adapt or correctly anticipate how to adapt to exploit whatever strategy you come forward with, so the best plan is to just produce “average” results”. I don’t believe this to be true, but the equilibrium strategy is still valid as a “base strategy”.

When to sacrifice yards for situation

by Mike Sommers

In "A Response To Brian Burke’s Washington Post Article", I stated that a team would actually be better served coming up short of the first down on 1st down. They would be better off setting up a 2nd and short than 1st and 10, unless they were able to surpass the threshold of 4 yards beyond the first down marker. All of these stats are based on normal teams who typically punt on 4th down. If they planned to go for it more optimally on 4th down, I suspect they would need even more than 4 yards to justify getting a conversion.
Before I go on about the exceptions, I thought it would be useful to get a bit more specific about the situations in which a 1st down conversion is not better than a 2nd and short.
Here is a graph and table of the expected points given the situation. While any 1st and 10 is more favorable than a 2nd and 3, a 2nd and 1 would still be 5 yards better than a 1st and 10. In other words, a 2nd and 1 on your own 29 yard-line is worth more expected points than a 1st and 10 on the 34.

Monday, November 5, 2012

Are punters getting better?




<br /> Google Visualization API Sample<br />

















by Michael Beuoy
Punts
The second most unloved play in the NFL (behind the extra point and, possibly, the Blaine Gabbert pass). When they show a punt on DirecTV's Redzone Channel, Andrew Siciliano actually apologizes, as if it were an errant f-bomb that made it past their tape delay.


The purpose of this post is to show some statistical love for this less glamorous element of the game. Much has been made of the improvement in field goal accuracy over the years. Do we see a similar improvement in punting? What I found is that punters are improving, having added about 4 net yards to their punts over the past ten years.

Data
For this analysis, I used the play by play data Brian Burke posts on his site, looking at seasons 2002 through 2011. From the fields and the play description, I was able to parse out which plays were punts, as well as the following data fields:
  • Field Position (where the team punted from)
  • Gross Yards (how far the kick went)
  • Net Yards
  • Result - Did the play end in a touchback, fair catch, downed by the kicking team, muff, return, or block?
  • Penalty Yards (if any) assessed on the punt
I only focused on "normal" punts for this analysis, meaning I excluded any punts that were blocked or that somehow resulted in the punting team retaining possession. If a punt had to be rekicked due to penalty, I am only counting the second "official" punt.

Wednesday, October 17, 2012

Response to Brian Burke's Washington Post article

By Mike Sommers


NB: I have also posted this on a site that I own and occasionally like to post to here.


I recently read Brian Burke’s article describing how coaches should avoid the mentality of trying to set up 3rd and short or 2nd and short and instead try to convert the first down.

It is not that I don’t agree with the article, but I wanted to consider several exceptions to that rule, and in the process came up with some interesting conclusions.

I can illustrate several instances where it’s best to NOT convert on first down. On 3rd however I can only think of 1, and it isn’t provable so much as it is intuitive, but I do have a statistical reference, unfortunately we just don’t have enough information to account for changes AS the play develops.

Saturday, October 13, 2012

Brees, Unitas and DiMaggio: 47-Game Streaks Fifty Years Apart, and that 56-Gamer, in Perspective.


by Jim Glass
Drew Brees is collecting well-deserved congratulations on breaking what many have long considered to be the greatest record in pro-football: the streak of 47 consecutive games with a touchdown pass thrown, set by John Unitas during the 1956 through 1960 seasons. In my youth that was often compared to Joe DiMaggio's famous "unbreakable record" 56-game hitting streak in baseball. Last week it was again.
Yet Brees tied-and-broke that record with no fewer than seven TD passes in his last two games, while looking as if he's going to "keep on going and going and going" like that trademarked battery-packed bunny.
So just how "unbreakable" should these records be considered to be?  With all the changes in the game that have occurred during the last 60 years, has Brees' streak really matched Unitas' as being "comparably unlikely," an equal achievement against the odds?  And how do these streaks actually compare to DiMaggio's.   Here's a quick take:

Running the Numbers
How unlikely were the Brees and Unitas 47-game streaks?   To adjust for the different styles of play of different times, a reasonable measure is the probability of the average team of each era (not quarterbacked by Brees or Unitas) scoring at least one touchdown by passing for that many consecutive games. 

Monday, September 10, 2012

Combining Win Probability Model With Live WP Graph




by Tom Baldwin

Andrew Foland provided a solution to this all the way back in January 2011, but it has not been implemented, perhaps because of the complexity of the solution, perhaps simply because nobody has got around to it yet, whichever the case I am here to provide a simple alternative and hope it gets implemented.

The problem is that of combining the prior strength of the teams – the expected difference in performance over a game, let us call this S, with the current state of the game as expressed as a probability, WP. To do this we must consider the total game time, 60 minutes, and the game time remaining, T, in minutes.

Friday, April 13, 2012

Comeback Wins/Losses: The Comeback Kings


by Clark Heins

For every comeback win there is a corresponding comeback loss, and one cannot be considered without the other. A comeback win occurs when the winning team overcomes a deficit at the start of the fourth quarter, at sometime during the fourth quarter or, if necessary, in overtime. Comeback wins have little to do with “comeback opportunities,” as the latter deal specifically with a point spread of eight or fewer points and include games that are tied in the fourth quarter. A comeback win can occur from any deficit and doesn’t deal with ties.

For the purposes of this study, I have made no attempt to credit a QB’s total of comeback wins/losses based upon whether or not he deserves them, as luck always plays a role. My totals are entirely based upon one criteria---who was the QB of record when the comeback win or loss was attained, regardless of how it was attained. As an example, I didn't credit Dan Marino, John Elway, Kerry Collins, and Warren Moon with comeback wins when they were injured during a game-winning drive and replaced by another QB. To do so would ignore the element of luck. Also, my calculations are based upon “QB starts” rather than “games played”, as it would be extremely unfair to use the latter stat for many of the QBs. “QB starts” isn’t perfect either, as several of the QBs mentioned here scored comeback wins or losses in relief.

Friday, February 24, 2012

Spygate: The Effectiveness of Cheating


by Paul Benjamin

Enough time has passed to evaluate the effect of Bill Belichick's cheating. The cheating took place from 2000-2006, and was ended early in 2007, giving 5 years of data since.

The known cheating consisted of two components, as revealed by Eric Mangini. First, the Patriots would tape opponents defensive hand signals. This permitted coaches to correlate the signals with the defensive alignments and figure out what each signal meant. Second, the Patriots used unregistered radio frequencies, so that the second time they played that team the offensive coordinator could watch the defensive signals and choose the perfect play to tell the quarterback. Normally, the referee cuts the registered radio frequency 15 seconds before the snap, so the offensive coordinator cannot communicate with the quarterback after the defense makes its substitutions, but the Patriots were the only team in the league that had radio equipment that could broadcast on multiple frequencies simultaneously. After the referee would cut the registered frequency, the quarterback could still hear the coordinator on the other frequency, so he could be told the defensive alignment he was facing and what play to call.

So the plays and blocking schemes were always perfect ones to exploit each defensive alignment.

Monday, February 6, 2012

Ring Probability Added


by Joe Harris
When arguing a QB's "greatness" people often quote the number of rings a player has as a definitive conclusion to a debate. For example, Dilfer is obviously greater than Marino because he has a ring. And there is nothing else to it. That statement takes the logic a bit further than most people would, but that is essentially how a lot of fans view the world. Whilst I am not a fan of this form of logic, I thought that it would be interesting to look at this concept through the lens of WPA or, more specically, RPA - Ring Probability Added.

Ring Probability Added
The basic idea is to take Brian's WPA stats and weight it depending on the magnitude of the game. For example, in 2004 when New England beat Carolina, Tom Brady essentially did enough to win the game single-handedly with +0.97 WPA. This corresponds to +0.49 RPA - he increased New England's chances of winning the Superbowl by 49%.