## The Manning Index

Last week, much was made of the fact that the Colts are 3-5 in playoff games started by Peyton Manning. Is Peyton a choker? I don’t think we’ve got sufficient evidence to make that claim, especially in light of the fact that the Colts have been the higher seed in only 3 of those 8 playoff games. In other words, the Colts’ postseason record in the Manning era is exactly what one would expect using an admittedly crude but very reasonable predictor. I thought that was interesting, so I decided to refine it just a bit and run that query for all the great past and present QBs.

First the refining.

I looked at all postseason games since 1978 and ran a logit regression (there’s the economics content in this post) with a win dummy as the output variable and the team records and game location as the inputs. For those curious, the formula is

```Probability of winning = (1 + exp(-.43(windiff)-.24(homefield)))^(-1)
```

where windiff = the given team’s regular season wins minus its opponents’ regular season wins and homefied = 1 if home, -1 if road, 0 if neutral site. So, for example, the 14-2 Patriots taking on the 12-4 Colts in Foxboro would have a windiff of 2 and a homefield of 1, which translates to an expected win probability of .748. Now all that’s left to do is tally up every quarterback’s expected wins (which is the sum of the win probabilities for each game) and his actual wins, and sort the list:

```                     Expected  Actual    Diff
-----------------------------------------------
Joe Montana              13.7      16      +2.3
Trent Dilfer              2.8       5      +2.2
John Elway               12.2      14      +1.8
Troy Aikman               9.2      11      +1.8
Mark Rypien               3.4       5      +1.6
Jeff Hostetler            2.5       4      +1.5
Brett Favre              10.2      11      +0.8
Drew Bledsoe              3.3       4      +0.7
Phil Simms                5.4       6      +0.6
Doug Williams             3.4       4      +0.6
Jay Schroeder             2.4       3      +0.6
Jim Everett               1.6       2      +0.4
Donovan McNabb            6.6       7      +0.4
Steve McNair              4.6       5      +0.4
Jim Harbaugh              1.7       2      +0.3
Kurt Warner               4.9       5      +0.1
Rich Gannon               3.9       4      +0.1
Stan Humphries            3.0       3      +0.0
Mark Brunell              3.0       3      +0.0
Jim Kelly                 9.3       9      -0.3
Kerry Collins             3.3       3      -0.3
Vinny Testaverde          2.4       2      -0.4
Dave Krieg                3.4       3      -0.4
Bernie Kosar              3.5       3      -0.5
Mike Tomczak              3.6       3      -0.6
Peyton Manning            3.8       3      -0.8
Neil O'Donnell            3.9       3      -0.9
Kordell Stewart           3.0       2      -1.0
Steve Young               9.1       8      -1.1
Jim McMahon               4.2       3      -1.2
Randall Cunningham        4.2       3      -1.2
Dan Marino                9.4       8      -1.4
Warren Moon               4.9       3      -1.9
```

Fine print: the list includes all quarterbacks whose careers began in 1978 or later (hence no Terry Bradshaw or Snake Stabler) and played in at least five postseason games. A QB was credited with a game played if he attempted 10 or more passes in the game.

Just to be clear, I believe that teams — not quarterbacks — win football games, so I’m not claiming this is the One True Measure Of Clutchness. Whether I like it or not though, wins are credited to quarterbacks in virtually every discussion about quarterback greatness. This is merely a way of putting a quarterback’s win-loss record into perspective.

I hate to admit it, but the deification of Tom Brady is getting tougher and tougher to argue with. This metric overvalues him just a tad by giving him credit for the 2001 victory at Pittsburgh (Bledsoe was probably more responsible for that win), but still. The probability of going 8-for-8 in the specific collection of postseason games Brady has played in is .004.

### 3 Responses “The Manning Index”

1. Anonymous says:

Very intriguing! It’d be interesting to tweak the logistic regression equation by a few input variables to factor in a) the quality of team the QB play’s for’s defense (i.e. average yards per game given up during the regular season), since, afterall, “defense wins championships” and b) is a team’s regular season win total as good of measure of “quality of team” as the 2nd half of the season would be? (that is, should 4 games won in September really count for as much as 4 games won in December?) Since you’re only looking at teams who made the playoffs by definition, I’d say teams who won more games later are better quality teams “at that point in time”, so would swap “windiff” with “difference in last 8 games’ winning percentage” between the teams (not counts). Of course, this level of data probably isn’t as easy to use as final regular season W/L is.

But, great article!! In looking at the names and trying to make some sense of things, it seems the QB’s at the top had “better coaches” during their playoff runs, in general, relative to the bottom bunch. Not to take anything away from the QB’s themselves. Obviously, you’d expect to see Montana and Elway at the top (and be leading your 4th quarter drive) no matter who their coach was. If Brady wins again this year, he will be right there with them!

Cheers,
TOM
(tom@data-for-all.com)

2. Anonymous says:

Montana seems to be the benchmark for regular season and playoffs, and Brady seems to step it up and not make any mistakes in the postseason…yet still isnt half the QB Montana is.
From seeing both play, I’d have to say that is right…
Good show!

3. Anonymous says:

Very cool, Doug.

I would be curious to see a similar study of how big of an advantage it really is for “cold weather teams” to host playoff games.

Yeah, New England probably wins a lot of their home playoff games, but is that number disproportionately large to the number of home playoff games San Francisco has won over the years?

-Richie
richiewohlers@gmail.com