SITE NEWS: We are moving all of our site and company news into a single blog for Sports-Reference.com. We'll tag all PFR content, so you can quickly and easily find the content you want.

Also, our existing PFR blog rss feed will be redirected to the new site's feed.

Pro-Football-Reference.com » Sports Reference

For more from Chase and Jason, check out their work at Football Perspective and The Big Lead.

Rerun: The other Dungy Index

Posted by Doug on November 2, 2006

I've got a busy week this week, so here is a re-run. This one ran in January of 2006 at sabernomics:

Tony Dungy’s teams haven’t fared particularly well, relative to expectations, in postseason games. So when, in this other post, I created a metric to measure such performance, I named it after the man. That was something of a cheap shot.

I’ll right that wrong here by noting that Dungy has a superlative record of producing and maintaining very good teams. In his four years at the helm of the Colts, they’ve won 48 games. Since 1990, only three teams have bettered that number during a four-year stretch and three more have equalled it. Yeah, I know, he inherited Peyton, Edge, and Marvin. He also inherited a defense that was a complete wreck. To average 12 wins a year over a four-year span is remarkable under any circumstances.

Let’s now examine the fraud known as Bill Parcells. He seems to get lots of credit for turning losers into winners. Most recently, he took over a Cowboy team that had been dreadful for several years prior to his arrival. Immediately, they were contenders in the NFC. There was a bump in the road the following year, but the Cowboys were once again in the playoff mix in 2005.

But what has he done, really? In the three years prior to Parcells’ arrival, the Cowboys were 15-33. That’s pretty bad. In the three years since, they’ve been 25-23. Better. Is that Parcells, or is that just what bad teams naturally do in the NFL these days: get better? Since 1990, there have been 35 teams that won between 14 and 16 games over a three-year span. These teams, as a group, would have to be considered similar to the Cowboy team that Parcells inherited. Their performance during the next three years could serve as a yardstick against which to measure Parcells’ performance. During the next three years, the other comparably bad teams averaged 22 wins and 0.85 playoff appearances. Bill has notched 25 wins and one playoff appearance. Solid effort? Yes. Miraculous turnaround? No.

For various reasons — some “natural” and some due to NFL tinkering — teams with good records tend to regress while teams with bad records tend to get better. That’s a fact that will surprise very few readers of this blog, I’m sure. But it’s at the heart of why I believe Dungy has a more impressive record than Parcells — than just about anyone — over the last few years. His teams, despite being good, have not regressed. During their most recent stints, Parcells has been aided by the forces of nature while Dungy has been fighting against them.

On the other hand, even someone like myself who possesses a deep and irrational hatred of Parcells would acknowledge that Dungy did inherit a better team than Parcells did. It would therefore be unfair to simply compare their records.

I want to quantify these ideas a bit. The first step is to establish a baseline. If a team won X games in 2005, how many games should they be expected to win in 2006? Regression can provide us with an estimated answer. A plain old linear regression including all teams since 1990 produces the following formula:

Next Year Wins =~ 5.51 + .317 * LastYearWins

Some quick checks indicate that it passes the smell test: plug in 8 and you get out 8, plug in 12 and you get out 9.3. Teams since 1990 that have won twelve games have actually averaged about 9.2 wins the next year. The formula models reality fairly well (not surprising, of course, since it was built to fit reality).

But this same formula doesn’t model the reality of 1973 or 1985 very well. Those were different times, so they require different formulas. I simply ran a separate regression for each of the three time periods 1970–1979, 1980–1989, and 1990–present. I’ve got no good reason for selecting those cutoff points. Probably 1978 (a bunch of rule changes) and 1993 (free agency) would be better cutoffs. Even better, I could ask J.C. to tell me about some statistical whizbangery that would examine the data and tell me the best place to draw the cutoffs. But I’m lazy, so nominal decades it is.

The next step is to go through each coach’s record, year by year, and compare his expected wins to his actual wins. Here, for example, is Dungy:


Expected Actual
Year Team wins wins Diff
=================================
1996 tam 7.7 6.0 -1.7
1997 tam 7.4 10.0 2.6
1998 tam 8.7 8.0 -0.7
1999 tam 8.0 11.0 3.0
2000 tam 9.0 10.0 1.0
2001 tam 8.7 9.0 0.3
2002 ind 7.4 10.0 2.6
2003 ind 8.7 12.0 3.3
2004 ind 9.3 12.0 2.7
2005 ind 9.3 14.0 4.7

That’s about 84 expected wins and 102 actual wins, making +18 marginal wins. He gets some credit for turning around a bad Bucs team. But he scores most of his points by keeping his teams at (or near) the top of the league consistently.

Before we get to the full list, a couple of technical notes are in order:

1. Only seasons since the 1970 merger are counted. Guys like Don Shula, whose career started before 1970, are included but the games prior to 1970 are ignored. These guys are asterisked.

2. I didn’t want to order the list by Total Marginal Wins because that would weight long careers too heavily. Ordering the list by Marginal Wins per season, on the other hand, wouldn’t give enough weight to long successful careers. So I ordered the list by (an approximation of) the probability that chance would produce the given record or a better one.


Expected Actual Marginal
wins wins wins
==============================================
*Don Shula 239 276 +36.5
Joe Gibbs 123 147 +23.6
Tony Dungy 84 102 +17.7
Mike Holmgren 117 138 +20.9
Marty Schottenheimer 159 183 +24.3
Bill Cowher 121 142 +20.8
Mike Shanahan 109 129 +19.8
George Seifert 97 114 +16.7
Bill Parcells 143 164 +20.9
Bill Walsh 83 96 +13.2
Andy Reid 60 70 +10.2
*Tom Landry 183 200 +16.5
*George Allen 77 88 +10.7
*Chuck Noll 191 208 +17.7
Marv Levy 129 144 +14.6
*John Madden 95 106 +10.8
Jon Gruden 65 73 +8.3
*Bud Grant 141 152 +11.3
John Fox 30 36 +5.7
Jimmy Johnson 71 80 +8.6
*Paul Brown 48 55 +6.9
Marvin Lewis 22 27 +4.8
Chuck Knox 185 198 +12.9
Bill Belichick 91 99 +8.3
Tom Coughlin 78 85 +7.1
Chuck Fairbanks 46 51 +5.3
Art Shell 42 47 +4.9
Bobby Ross 72 78 +6.2
Dennis Green 101 108 +7.0
Mike Sherman 52 57 +4.6
Jack Del Rio 23 26 +3.1
Barry Switzer 37 40 +3.4
Jeff Fisher 90 96 +5.6
Dick Vermeil 117 124 +6.4
Wade Phillips 41 45 +3.5
Mike Martz 53 57 +3.7
Mike Ditka 119 124 +5.5
Don Coryell 112 117 +5.3
Red Miller 39 42 +2.9
Brian Billick 58 62 +3.8
John Ralston 38 41 +3.0
Dan Reeves 189 195 +6.2
Jerry Burns 50 53 +2.9
Jim Mora 123 127 +4.2
Walt Michaels 42 45 +2.4
Bum Phillips 86 89 +3.1
*Joe Schmidt 28 30 +1.6
John Robinson 74 75 +1.6
Mike Tice 31 32 +1.1
John Mackovic 29 30 +1.0
Raymond Berry 44 45 +0.8
*Charley Winner 21 21 +0.6
Jim Fassel 58 58 +0.8
Tom Flores 103 104 +0.8
Jack Pardee 90 91 +0.7
Wayne Fontes 64 64 +0.5
Steve Mariucci 73 73 +0.3
Buddy Ryan 56 56 +0.1
Ron Meyer 60 60 +0.1
Jerry Glanville 61 61 +0.0
Forrest Gregg 84 84 -0.2
Ted Marchibroda 92 92 -0.4
Dan Devine 32 31 -0.7
*Nick Skorich 36 35 -0.7
Pete Carroll 34 33 -1.1
Rick Forzano 24 23 -1.0
Tommy Prothro 51 49 -1.7
Sam Rutigliano 56 54 -1.8
Don McCafferty 39 38 -1.4
Jack Patera 45 43 -2.2
Jim Haslett 47 45 -2.3
Jim Hanifan 46 43 -2.5
Herman Edwards 41 39 -2.5
Dick Jauron 38 35 -2.7
Monte Clark 59 56 -3.6
*Lou Saban 52 49 -3.5
Dave Wannstedt 89 85 -4.5
*Dick Nolan 71 66 -4.2
Joe Walton 58 54 -4.0
Neill Armstrong 33 30 -3.3
*Ray Malavasi 45 42 -3.7
Leeman Bennett 60 55 -4.7
*Norm VanBrocklin 40 36 -3.9
Bart Starr 65 60 -5.3
*Hank Stram 58 53 -4.9
Ray Rhodes 42 38 -4.2
Gene Stallings 28 24 -4.5
Butch Davis 30 25 -4.6
*Alex Webster 32 27 -4.7
John McKay 56 49 -7.1
Sam Wyche 93 84 -8.3
Norv Turner 67 60 -7.7
June Jones 24 19 -4.5
Ray Perkins 54 46 -7.7
John North 19 14 -4.8
Bill Johnson 29 25 -4.9
Mike McCormack 34 28 -6.5
Bill Arnsparger 17 11 -5.1
Dave McGinnis 21 16 -5.3
Dennis Erickson 48 40 -7.6
Gregg Williams 23 17 -5.6
Dom Capers 57 48 -9.4
Darryl Rogers 27 20 -6.8
Rich Kotite 48 40 -8.3
Frank Kush 18 12 -5.9
Abe Gibron 19 13 -6.1
Ron Erhardt 27 21 -6.1
Vince Tobin 37 29 -8.1
David Shula 34 26 -8.2
Paul Wiggin 20 14 -6.5
*Weeb Ewbank 32 24 -7.5
Mike Riley 21 14 -7.0
Lindy Infante 46 36 -10.1
Dave Campo 22 15 -7.2
Dan Henning 50 38 -11.8
Marion Campbell 53 39 -13.8
Bruce Coslet 58 44 -14.0
Joe Bugel 35 24 -11.5
Kay Stephenson 21 12 -8.9
Ed Biles 22 11 -11.3

How you weight the relative importance of regular season performance versus postseason performance is up to you. But either way, it’s tough to come up with a better candidate for best post-Merger NFL coach than Joe Gibbs.

This entry was posted on Thursday, November 2nd, 2006 at 5:01 am and is filed under General, History, Statgeekery. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.