Sunday, November 12, 2006

Kickoff distance more reliable than field goal percentage

Nice NY Times article today on NFL kickers by Aaron Schatz, of Football Outsiders. (Get it here quick before it becomes pay-only.)

Schatz notes that kickers are inconsistent in field goal success, but quite consistent in kickoff yardage. For instance, Mike Vanderjagt's field goal percentage for the last five years has been (2002 to 2006, respectively) a bouncy 74, 100, 80, 92, and 77. But his kickoff yardages from 2002-2004 were a steady 59, 60, and 58. (This year, he's at 57.3, the only kicker in the league below 60.)

Schatz concludes that teams would be better off concentrating on the kickoff stat when making personnel decisions, since the field goal percentage is such a poor indicator of the player's actual talent.

A couple of comments:

1. Kickoffs are exactly the same every time, while field goal attempts are from different yardages. Perhaps much of the apparent variance in FG percentage will disappear after adjusting for distance? In any case, the FG percentage is binomial in, say, 35 attempts, while the kickoff distance is (presumably) normal in about 60 (?) attempts, so you could probably figure out some variance details if you wanted.

2. Assuming a good kicker can net an extra two yards on a kickoff, and 60 kickoffs a year, that's 120 yards. At 12 yards per point, that's 10 extra points. 10 extra points is about 3 missed field goals., which is about the difference between an 85% kicker and a 75% kicker. Schatz is implying that kickers are so inconsistent that you can't really tell who's the 85% and who's the 75% kicker, so concentrate on the kickoffs. Fair enough.

3. If kickers are inconsistent, doesn't that imply that much of their apparent performance is due to luck? Therefore, you have to regress them to the mean quite a bit. That means the range of field goal skill could be very narrow, so narrow that you should almost ignore field goal percentage altogether.

4. Kicking two yards deeper means that the kicking team has to run two yards farther to get to the kick returner. Shouldn't that mean the returning team has a bit of extra time to run the ball back a little farther? Or does the extra time the ball is in the air negate that?

5. Can't they just give the guy a test before hiring him? Make him kick field goals from various distances every half hour for a couple of weeks. That should give you enough information to make a decision. Sure, there's no pressure, and no defense bearing down on him, and no crowd noise, and all that, but isn't that still better than nothing? Do teams already do this? Is there a radar gun for kickers?

Some of this stuff might already have been studied … I just got my copy of Schatz et al's
Pro Football Prospectus a few days ago, so maybe I should read up.

(Thanks to The Wages of Wins Journal for the pointer.)

UPDATE: more from Schatz here.


At Tuesday, November 14, 2006 3:08:00 PM, Blogger Bob Timmermann said...

From what I've read, football teams generally have impromptu contests to decide between kickers. They'll have one guy try five kicks from 25 yards out and see how he matches up against the other guy. Then they keep going back in distance.

Kickoffs are almost always included too.

I don't know how you can have a practice situation duplicate a game situation for a field goal. Practices are often done on finely manicured fields without screaming fans, swirling winds, and the realization that several million people are going to be really angry at you for missing the kick


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