Roundup 9/25/10

Advanced individual player stats will be updated immediately after each game this season.

Game probabilities will start for week 4. They'll be featured at the NY Times again this season.


TJ uses EP to analyze a big play call in the DEN-SEA game from last weekend.

NYT article on the 3-4

From the Advanced NFL Stats Community reboot:

Dan Schlauch on placekicker salary distribution. Leave some comments and give Dan some feedback.

John Candido is parsing weekly play-by-play for everyone this season. If you use John's data, be sure to leave behind a thanks. I'll be updating 2010 data periodically, but not every week.

Keep the submissions coming! Thanks again to Ed for tending to 'Community.'

This is a really interesting analysis by Adam Dorhauer of rounding errors on football yardage gains. (Helmet-knock: Tango) As everyone knows, gains are always rounded to the nearest whole yard. For a RB with a lot of carries, it's conceivable that these errors could have a significant effect on his season carry stats.

But the more I thought about it, the more I realized this probably isn't the case because scorers technically don't call out the gain of the play. The gain is deduced from where the ball is spotted. Any one single spot itself may have a +/-.5 yd error, but all gains must reconcile to the total gain of a drive. Therefore, the errors are not independent. A large positive rounding error will be followed by a subsequent negative error.

For example, if a team has 2 plays in a row, and one goes for 4.5 yards but is scored as 4, and the next goes for 5.5 yds, it can't be scored as 5. It must be scored as a 6 yd gain because the ball is very clearly 10 yds further down field, not 11. Although a starting RB won't account for all his team's gains, he would account for a very large share of them, which narrows the distribution of his errors considerably. This doesn't invalidate Adam's analysis because he has set an upper-bound to how high the rounding errors could accumulate.

Jason Lisk (JKL) of PFR is now also posting at "The Big Lead". Here is a sample.

Chase breaks down the league leaders in Net YPA and RYO2 (Run yards over 2) at Fifth Down.

Ben Alamar is trying to record the time in the pocket for all pass plays this season, partially in an attempt to grade offensive lines and offensive linemen. This seems ambitious and interesting, but isn't there a big problem? If a QB throws the ball, how do we know how long he would have had? It's like trying to figure out how far a tank of gas will get you, except that you stop at your destination before running out 95% of the time. Seems like this would inject lots of bias in the data, and it's probably why Alamar is confused by the results so far.

What makes a high-ranked tennis player, breaking serve or holding serve?

Evidence that home field advantage is not a function of attendance.

Does payroll matter less in baseball lately, or is it just noise in the data?

Team-by-team salary cap numbers, if there were a cap. Even though it's an uncapped year, the effective-cap payroll data is useful because cap numbers best express the true present-year payroll of a team. Contracts can be so convoluted, with signing bonuses, roster bonuses and incentives, that actual salary numbers can be very misleading.

Chris at took Chase Stuart's analysis of how often week one winners and losers make the playoffs. Week one winners make the playoffs about 50% of the time, and losers make it about 25% of the time. Chris ran a simulation that found how much of the advantage of the week one win is due to having a head start to a better season record, and how much is from the implication that a winning team is a good team. Chris writes: 69% of the success of week-1-winning teams in making the playoffs. The remaining 31% of the benefit of winning in week 1 comes from the fact that you might actually be a good team.

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2 Responses to “Roundup 9/25/10”

  1. DA Baracus says:

    That home field advantage article has little to do with football. In baseball HFA comes from the park's dimensions and how it plays. In football, attendance can help you, just look at that game a few years ago in Seattle where the Giants had something like 12 false start penalties, because of the crowd noise.

  2. Ian says:

    Just reading TJ's EP article, what struck me was how similar the EP values of the FG or 4th down calls were if you forgot about the 0.7 EP a team gets for receiving the ball.

    I wonder how many of the ultra-conservative calls we see from coaches on 4th down arise from forgetting to include in their calculation that the opponents get the ball from the kickoff.

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