Monday, March 31, 2008

In the Trenches: An Intro

For the past four Sundays the NFL Network has been "replaying" five games from each week of the 2007 season. I've decided to go back and look at the offensive line play in all of these games using the Blocker Rating system I introduced following the Super Bowl.

I hope that by charting the 2007 games I can work some of the kinks out of the system, and be more prepared to chart games and post about them throughout the 2008 season. I've made some slight modifications to my rating system, and really it's still in flux. I thought about a major overhaul, or possibly doing two ratings: an Effectiveness Rating, which would basically be the simple Blocker Rating I discussed in the Super Bowl post; and a Quality Rating, which would better account for "dominating" blocks that eliminate a defender from a play no matter what might happen, as well as successful blocks of more than one defender on a play, while discounting blocks that were part of a double team. But after charting one half of a game using the Quality Rating system, I could see that it would be so time consuming that there would be no way I could manage to keep at it over the course of a season. Instead, I'm experimenting with ways to account for some of this info in my simple rating system, without adding too much time to the process. And besides, I'm not entirely convinced that the Quality Rating would have yielded significantly better results.

Here are some of the key points to know about this rating system:

1. 10 is the highest rating, whether for a game or a season (in effect, a 10 is a "perfect game"). The early returns suggest that perfect pass blocking games will not be rare ("uncommon" would seem to be more accurate), but perfect run blocking games will be scarce.
2. Once I have enough data I will post the averages of each position to provide a context in which a player's perfomace/rating can more easily be judged. Eventually this may lead to a "value over average" rating.
3. Blocker Rating's main limitation is that it doesn't account for how much a lineman might be asked to do. For instance, a left tackle who effectively blocks, say, Dwight Freeney one-on-one on a pass play will score the same as the left guard and center who effectively double team Ed Johnson. Similarly, a right guard who whiffs on his pull block, allowing Gary Brackett to stuff his running back for no gain, will score as low as the right tackle whose backside cut block fails to take out Robert Mathis regardless of whether Mathis is able to assist on the tackle or not (the assumption being that anything can happen on a given play, and hence, every defender who can be taken out of the play should be in case, for example, the running back needs to cut back or a fumble needs to be recovered).
4. Something of a minor point, but in case someone wonders about this: run blocking and pass blocking are defined by whether a play is a run or a pass. That might seem obvious, but it could potentially be defined otherwise. For instance, the blocking on a play-action pass calls for run-blocking techniques, while a draw play typically has the linemen feigning pass protection. Screen passes are almost their own animal, calling for some linemen to pass block, while others only initially fake that before slipping out to get ahead of the receiver, calling for skills closer to those used in the running game.
5. The ratings are not defense adjusted. That is, there's no adjustment whether a guard is facing a tough task like, say, Albert Haynesworth, or if he's battling Claude Wroten all day. (I am going to collect some opponent data, and by the end of the season I should be able to comment on the results.)
6. After charting a couple of week one games I changed it so that passing plays of 2 or fewer seconds are no longer included. Aborted plays are still not counted and neither are false starts, but plays with offensive holding are now charted, as are any plays where the penalty is on the defense (although if an offensive lineman is beat because the defensive man was offsides, it's not counted against him).
7. Games charted using NFL Replay are a necessity as long as I have a day job to attend to. The final Blocker Ratings from these games are not "official" in that these broadcasts don't show every play. However, enough plays are shown to get a representative sample of a player's performance, especially as the total plays accumulate over the course of a season.
8. I can't reiterate enough: This is a very simple rating system, so that I actually have enough time to chart as many games as I can record. Although quite a bit is left unaccounted for, I've seen enough already to believe that my Blocker Rating gives a good indication of how well, or poorly, a linemen has played. If I continue to be pleased with the results, I might eventually recruit other volunteers to chart games so that only full games are charted and so that a season can be completely captured. But I won't be doing that until I'm fully comfortable with this and have had more time to tweak the rating system.

There are probably other key points escaping me right now. I'll update this post as they occur to me.

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