Weekly Roundup

Sabermetric Research points to this King Kaufman column in Salon.com. Kaufman takes sports writers to task for not appreciating advanced statistics. Sports writers and even some coaches are often dismissive of stats, and some even wear their ignorance as a badge of honor. Baseball is going through a quiet transformation based on advanced statistics. Stats are the cutting edge of the sport, and writers would do well to get on board. The way I see it, statistics is just a tool for learning from large sets of facts. Everyone relies on statistics one way or another. You can chose to do it well or do it poorly. Judging from the interest in this site and others, there is a sizable audience hungry for something other than the same old tired storylines we get from columnists and analysts.

Game theory could help improve the overtime problems in the NFL. This article talks about how to fairly divide something between two people. One of the best solutions is the I'll cut you choose method. So if two people splitting a piece of cake, one person would cut it in half, and the other picks which half he wants. The person cutting has an interest in making the division as fair as possible. Overtime could work the same way. The coin flip winner picks the yard line for kickoff, and the other team gets to chose whether to receive or kick. I don't think most traditionalists would like this idea, but neither team could complain about the outcome.

ZEUS chimes in on the Titans' decision to tie Ravens with a field goal instead of go for the first down on 4th and inches. Here was my take. But let me skip to the last chapter for everybody. It is almost always better to go for the first down, even up to 4th and 7 on a team's own side of the field in most cases. About the only times an NFL team should kick are on 4th and very long, or if time is expiring and the kick will win or tie the game.

ZEUS also thinks Coughlin was right to go for it against the Eagles. One thing about ZEUS, though--From what I can tell, the software is a simulation-based model. This means that it takes the current state of a game including score, time, field position, etc. and randomly simulates a game from that point forward. It does this 'millions' of times to estimate average win probabilities (that it calls game winning chance--GWC).

To me, this approach is fraught with problems. You'd have to model so many things so precisely to get a reliable result. The distributions of all possible play results for all the possible combinations of cirmcumstances simply could not be modeled with any reliability. You'd need to make a lot of assumptions, and the results are going to be very sensitive to those assumptions. It wouldn't be much different than playing out a game on Madden in auto-computer mode a million times. It just depends on the fidelity of the simulation. On the other hand, the advantage of this approach is that you can tweak the distributions to reflect specific team strengths and weaknesses.

Individual team abilities are mitigating considerations in kick or go-for-it decisions, but my take is that these factors are often overstated. Take the Ravens-Titans game. As I pointed out earlier this week, Baltimore had only scored on 2 of 10 possessions up until Fisher's decision to kick. That might indicate that the Titans defense could almost certainly count on stopping the Ravens offense. But the NFL average is 3 scores every 9 drives, not significantly different from 2 out of 10, and Baltimore went on to score to make it 3 out of 11. How much does under- or over-performance within a game predict performance later in a game? PFR took up that question and finds only about 25% of a team's under-performance in the first 3 quarters carries through to the 4th quarter.

Home field advantage (HFA) has been a focus of sports science for decades. We can quantify the strength of its effect pretty easily, but what are the causes? Is it travel fatigue, time zone change, weather, crowd noise, the shape of the field or cut of the grass, or referee bias? I think we now have pretty solid evidence that a large part of HFA comes from environmental familiarity.

The possible effect of general unfamiliarity was summed up well by a commenter: "From a psychological standpoint, performance could be subtlety infuenced due to players being in a somewhat unfamiliar environment due the small but cumulative effects of orienting to the new environment. This could be many things— the locker room, where the sun comes in over the stadium, the overall “feel.” All of these small distractions could influence performance–a performance that involves instantaneous decision making and physical reaction times. Research has shown that orienting to even environments that are somewhat unfamiliar influence memory, judgment, decison making, etc."

PFR took a look at HFA when opponents are familiar with each other. I thought that this might be what explains why HFA diminishes throughout a game. My suggestion was that because visitors are more familiar with environments when playing divisional opponents than when playing other opponents, we should see a reduced effect. And sure enough, that's exactly what we see. Division rivals not only have a reduced overall HFA, the quarter-by-quarter decline in HFA is shallower. To me, this is evidence that a good deal of HFA in the NFL is due to overall environmental familiarity. I think this is very interesting, and it comes mostly from loose collaboration from people who've never met. Twenty years ago, before the internet, research like this wouldn't be possible. We're not curing cancer, but it is interesting and useful. Further comments here.

Smart Football dissects the deep crossing route.

The Numbers Guy takes a look at rare NFL scores. The Chargers-Steelers 11-10 score is not the only unique score this year.

I really liked Jim Glass's comments about the distinction between the "best team" and "the campion."

Contributer jjbtnw looks at 3rd down and 6 situations. Should teams run more often?

Dean Jens takes a stab at modeling punting and field goal kicking.

Pacifist Viking has an excellent article about the classical correlation/causation fallacy. PV debunks a lot of analysis by Cold Hard Football Facts. But I do enjoy CHFF, but not because of the analysis there. The stats aren't always the soundest, but the analysis is much better than most other sites. The writing is excellent and I like the historical perspective they add. I wish I could write like that.

An article at NFL.com talks about which stats matter to coaches.

Sometime shortly I'll have a new Win Probability tool available. You can enter a game state and calculate the WP. I originally made it as a tool for myself when analyzing things such as 4th down decisions, but thought other people might find it interesting too. So I spiffed up the interface and will have it up and running soon.

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2 Responses to “Weekly Roundup”

  1. Anonymous says:

    Do you have a regular job, too, like 40 hrs/week? If so, do you have more hours in a day than I do, how the hell do you do all of this?

  2. Jim Glass says:

    I think Pacifist Viking is exactly right on the interceptions correlation v causation issue, and that moreso than the running-winning correlation, this is still largely unappreciated in many quarters.

    [] Logically, teams that are behind to begin with throw more often to catch up (especially as it gets late in the game), throw against Ds that are expecting it, thus throw "uphill" against aggressive pass rushes and DBs sitting on the pass ... and so throw more picks at a higher rate than teams that are winning.

    [] Empirically one can see this in QB situational splits, as NFL stats show QBs have significantly higher passing ratings when playing ahead than behind.

    E.g. from my clip file for 2006...

    Tom Brady's passing rating when:
    Ahead by 9-16 .... 136
    Ahead ............. 99
    Behind............. 67
    Behind by 9-16 .... 57

    Drew Brees, as MVP runner-up:

    Ahead .............. 106
    Behind .............. 87

    Tony Romo:

    Ahead .............. 121
    Behind .............. 87, etc.

    So the quality of a team's defense can materially affect the quality of its QB's play and his rating -- another example of the QB getting both excessive credit and blame in a team game ... but I digress.

    [] Anecdotally, I have the misfortune to be a long-time Jets fan, and Pennington 2007-2008 is a great example of all of the above.

    2007: The Jets had a dreadful awful D during the first half of the season while CP was starting. Time and again he had the lead for most of the game but after the D collapsed in the second half, he spent the last minutes chucking uphill to try to come from behind. Time and again the game ended a loss after he threw a bad-looking pick.

    Jets fans' reaction: "Killer pick after killer pick! Popgun with his noodle arm can never carry this team to a big win, especially from behind when you really need it".

    So the guy was benched and run out of town and replaced with Favre, though career-wise CP had one the lowest pick rates in NFL history ... and replacing him, or anyone with Favre to reduce bad picks ... hey! ... but I digress again.

    2008: Penny returns to near league-best pick rate with 7 in 16 games.

    But then, in the playoffs against a much superior Ravens team, playing almost all the way from behind, he throws 4 in one game.

    The Jets fans who had wanted to get rid of him say, "See, we were right! Popgun and his noodle arm can never beat a good team -- he lost that game by throwing 4 picks! How could they win when he did that?" CHFF would probably agree.

    But I'd suspect there was some causation working the other way around. And that teams that don't recognize it can make personnel decisions that may leave them without a decent QB for years to come ... but enough digression.

    This isn't to deny that "bad picks" are killers that cause a lot of losses, but ISTM picks could be sorted into three categories...

    1) Meaningless, like hail marys in lost games, completely caused by being losing, not affecting the outcome.

    2) Under duress but unfortunate -- such as while trying to come from behind playing "uphill". This is some on the QB, you don't want to throw them, they can bury a team's chances in a game. But the QB is under a handicap, and the team was probably going to lose anyhow, so it doesn't really cost the game.

    3) True "killer", game-costing picks -- like Favre opening the season-ending Mia game deep-throwing 10 yards over an open receiver's head and following up with picks on a screen pass and 2-yard checkdown.

    ISTM that an "ideal" passer rating would weight all these differently, and so might come to quite different conclusions than systems like the NFL's that treat all picks the same. And that with game logs and spreadsheets it might be getting practical to do, quantifying the cost of different kinds of picks. And that that could help keep teams from being left QB-less for years to come after running a good QB out of town for apparently making too many bad picks that really weren't so bad ... oh, but I digress again ... it's hard being a Jets fan.

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