## Similarity Scores for 2009 teams, part I

Posted by Jason Lisk on October 20, 2009

I'm going to do some team similarity scores like what Doug did a couple of years ago. I'm not going to use the same methodology (not that either is better than the other), because I'm not going to look at specific game results. Rather, I am going to look at a team's overall profile, in terms of wins/losses, points scored and allowed, and yardage for and against.

Like Doug, I'm not putting a tremendous amount of time into deciding how to weigh each factor. I just went with adjustments that generally felt about right, and then made sure the results passed the sniff test.

Anyway, I'm looking at the the overall points scored and allowed through six games, as well as the total net passing yards and total rushing yards for and against, along with team record. Here's the method I'm using to come up with similarity scores for each team who played a 16-game schedule from 1978 to 2008:

- Start with 1000 points;
- Subtract 5 points for every 1 point difference in Points Scored;
- Subtract 5 points for every 1 point difference in Points Allowed;
- Subtract 5 points for every 1 point difference in Net Point Differential;
- Subtract 1 point for every 10 yard difference in Net Passing Yards (that is, passing yards with sacks yards lost included) on offense;
- Subtract 1 point for every 10 yard difference in Net Passing Yards Allowed on defense;
- Subtract 1 point for every 10 yard difference in Rushing Yards on offense;
- Subtract 1 point for every 10 yard difference in Rushing Yards Allowed on defense;
- Subtract 1 point for every 10 yard difference in Net Passing Yards Differential (Offensive Yards minus Defensive Yards allowed);
- Subtract 1 point for every 10 yard difference in Rushing Yards Differential (Offensive Yards minus Defensive Yards allowed); and
- Subtract 100 points for every difference of 1 win.

I'm going to just quote part of what Doug wrote, because it holds true here.

In some sense, this exercise is just a whole lot of work to get (I'm assuming something very close to) the same results you'd get by running a simple regression of wins versus [scoring margin and yardage differentials]. But I like this method better, because it's not a black box.

You say the Bears should expect to win X games this year. Your friend calls BS: haven't you seen how dominant they've looked? If regression is what you've got, it's tough to give a decent counterargument unless he understands regression. But this method lays the reasoning right out there in a crystal clear way: the 1986 Falcons won their first two games by a combined 41 points and they ended up winning 7 games. The 1994 Seahawks won their first two by scores of 28-7 and 38-9, and they finished at 6-10. That is, of course, the same kind of information that your regression was taking into account, but it's just so much more transparent here.

Also, while I doubt it's actually happening here, this method is theoretically capable of picking out subtle combinations of things that regression wouldn't tell you, because you wouldn't think to ask it.

I'll just add to that last point. While I'm expressly measuring wins, plus points and yards, plus the net differences between offense and defense in those categories, it is probably picking up additional factors. If a team has a good point differential but the yardage doesn't matchup, it might be indirectly measuring teams that have good turnover ratios and good special teams. Certain combinations may indicate a team that has played a tough or easy schedule during the first six weeks, that sort of thing. A team that has the same differential and yardage, but 2 more losses, may indicate something, whether good or bad, going forward, about what happened in some of those individual games, even though I am not directly measuring at the individual game level. Whether those have any meaning, I don't know. They may be just random pockets of information.

My method doesn't know anything about these teams, other than the series of cold, hard numbers input in the formula. It doesn't know that the Jets are quarterbacked by a rookie that has been up and down, though, eerily, three of the top ten comparable teams also featured rookie quarterbacks. It doesn't know that the Vikings were the media darlings before the first game, or that the Broncos were not expected to be this good. It just sees one 6-0 team that it favors to win more games going forward because of the low points allowed and great passing defense. It doesn't know that the same team had a historically bad defense the year before, or that there was a coaching change, or what key changes are responsible for the improved defensive play. It doesn't know that the 2009 Patriots have a future Hall of Famer at quarterback, even though six of the top ten comparable teams were also quarterbacked by a current or future Hall of Famer (in years they did not win a Super Bowl, by the way). It doesn't know that Pittsburgh is the defending Super Bowl champion.

I'm going to start today with all the teams that have played six games, and have won at least three of them. Later this week, I will post the teams that have lost more than half their games and have played six, and next week, I will add the remaining twelve that have had a bye to this point, after they have also played six games.

For each team, I list the weighted average wins of the top ten comparables over the last ten games of the season. I also give a playoff chances percentage. This is also weighted on comparables, and based on the percentage chance of making the playoffs with each win total, based on 1990-2008, when the league has had six playoff teams in each conference. No team has made it with seven or fewer wins, so I assigned 0 to any win total under 8. Teams with 8 wins have made the playoffs 12% of the time, while teams with 11 wins have made it 98% of the time, and no team with more than 11 wins has failed to make the playoffs.

As a result of this, you see some interesting results where some teams have a higher average expected win total, but a lower playoff percentage, depending on the variance of their comparables. I list the teams in descending order of playoff chance percentage. The first column is the similarity score, the second is the comparable team, and the last two columns list the comparable team's record in the first six games, and last ten games.

2009 DENVER BRONCOS

weighted wins (last 10): 6.77

playoff chances: 99%

============================================================== 809 PHI 1981 6-0 4-6 763 NYG 1986 5-1 9-1 747 NOR 1991 6-0 5-5 736 NYG 1990 6-0 7-3 733 CHI 1988 5-1 7-3 723 OTI 2008 6-0 7-3 714 CLE 1994 5-1 6-4 708 JAX 1999 5-1 9-1 706 RAM 1978 6-0 6-4 703 PIT 1978 6-0 8-2 ==============================================================

MINNESOTA VIKINGS

weighted wins (last 10): 5.89

playoff chances: 90%

============================================================== 850 KAN 2003 6-0 7-3 779 DAL 1983 6-0 6-4 769 MIN 2003 6-0 3-7 762 MIA 2002 5-1 4-6 756 SDG 1994 6-0 5-5 755 WAS 1983 5-1 9-1 727 DEN 1986 6-0 5-5 712 CIN 1988 6-0 6-4 688 CHI 1985 6-0 9-1 671 RAM 1988 5-1 5-5 ==============================================================

NEW YORK GIANTS

weighted wins (last 10): 6.08

playoff chances: 84%

============================================================== 804 NWE 1980 5-1 6-4 781 MIA 2002 5-1 4-6 771 RAM 1980 4-2 7-3 757 DAL 1986 4-2 3-7 754 MIN 1992 5-1 6-4 744 WAS 1983 5-1 9-1 729 DAL 1995 5-1 7-3 724 JAX 1997 5-1 6-4 724 SFO 1983 4-2 6-4 715 PIT 1979 5-1 7-3 ==============================================================

NEW ENGLAND PATRIOTS

weighted wins (last 10): 6.27

playoff chances: 80%

============================================================== 827 BUF 1981 4-2 6-4 823 SFO 1986 4-2 6-3-1 806 KAN 1990 4-2 7-3 782 GNB 2001 4-2 8-2 769 RAM 2003 4-2 8-2 767 BUF 1992 4-2 7-3 764 SFO 1996 4-2 8-2 764 DAL 1999 4-2 4-6 752 SFO 1995 4-2 7-3 747 SDG 2001 4-2 1-9 ==============================================================

BALTIMORE RAVENS

weighted wins (last 10): 6.08

playoff chances: 57%

============================================================== 904 DAL 2006 3-3 6-4 865 DEN 2000 3-3 8-2 830 GNB 2003 3-3 7-3 819 SDG 2008 3-3 5-5 806 NOR 2008 3-3 5-5 798 PHI 2008 3-3 6-3-1 791 RAV 1997 3-3 3-6-1 787 CHI 1995 4-2 5-5 783 DEN 1985 4-2 7-3 776 PHI 1988 3-3 7-3 ==============================================================

CINCINNATI BENGALS

weighted wins (last 10): 5.39

playoff chances: 57%

============================================================== 916 BUF 1994 4-2 3-7 915 DAL 1991 4-2 7-3 870 CLE 1983 4-2 5-5 852 ATL 1995 4-2 5-5 840 KAN 1997 4-2 9-1 838 DET 2000 4-2 5-5 834 NWE 1984 4-2 5-5 831 CLT 1995 4-2 5-5 830 DET 1999 4-2 4-6 829 PHI 1996 4-2 6-4 ==============================================================

PITTSBURGH STEELERS

weighted wins (last 10): 4.79

playoff chances: 45%

============================================================== 903 DAL 2005 4-2 5-5 848 ATL 1994 4-2 3-7 848 PHI 1994 4-2 3-7 841 RAI 1985 4-2 8-2 826 PHI 2005 4-2 2-8 810 PIT 1981 4-2 4-6 810 WAS 2005 4-2 6-4 806 NYG 1985 3-3 7-3 791 NOR 2001 4-2 3-7 789 GNB 1995 4-2 7-3 ==============================================================

NEW YORK JETS

weighted wins (last 10): 5.39

playoff chances: 39%

============================================================== 897 PHI 1978 3-3 6-4 866 MIA 1983 3-3 9-1 841 NYJ 1991 3-3 5-5 831 RAV 2008 3-3 8-2 824 CLT 1989 3-3 5-5 818 MIN 1978 3-3 5-4-1 816 SDG 1990 2-4 4-6 813 CLE 2004 3-3 1-9 809 NOR 2000 3-3 7-3 802 SEA 1993 3-3 3-7 ==============================================================

JACKSONVILLE JAGUARS

weighted wins (last 10): 4.39

playoff chances: 35%

============================================================== 839 NOR 1985 3-3 2-8 828 WAS 2003 3-3 2-8 821 NYG 1988 3-3 7-3 809 NYJ 2006 3-3 7-3 784 NOR 1998 3-3 3-7 772 TAM 1984 3-3 3-7 769 SEA 2006 4-2 5-5 764 MIA 1989 3-3 5-5 753 PHI 1995 3-3 7-3 750 BUF 1997 3-3 3-7 ==============================================================

HOUSTON TEXANS

weighted wins (last 10): 5.43

playoff chances: 31%

============================================================== 876 HTX 2004 3-3 4-6 847 HTX 2007 3-3 5-5 840 WAS 1988 3-3 4-6 839 KAN 1985 3-3 3-7 775 RAM 2004 2-4 6-4 773 NWE 2002 3-3 6-4 764 PIT 1995 3-3 8-2 757 MIN 1985 3-3 4-6 745 CLT 2008 3-3 9-1 741 PIT 1984 3-3 6-4 ==============================================================

Nice to see that some measures support Raven fandom. You'd think they lost each of the last 3 by 30 with how many people are bad talking the Ravens after a miss FG, a penalty ruined mess, and a Bengals kick in the last 30 or so.

Interesting. A couple of observations:

Strange that Minnesota and the Giants both have strong similarity with the 2002 Dolphins, yet they only have one other team (1983 Dal) in common.

I wonder if your penalty of 100 points per win is too small. Each team has other teams of the same W-L record as their primary group of similar teams. Maybe that's what you're going for?