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Backup quarterbacks and the element of surprise

Posted by Doug on May 8, 2009

From a reader named John Worrall, this appeared recently in my email box:

I have a theory that says that backup players that come into games perform at a very high level, because the opponent gameplanned for a different player. For example, when Joe Montana would go down with an injury and Steve Young came in, the opposing defense got a COMPLETELY different kind of QB than they were ready for, which meant Steve Young would have a huge game.

With all this new game log data we've got, we can test this kind of thing out.

The first thing I wanted to do was build a database query that would find all instances where one quarterback was unexpectedly replaced early in the game by another. I eventually decided to find all instances where:

1. the starting quarterback in a particular game threw five or fewer passes (and no interceptions), and the quarterback who replaced him threw 20 or more passes

and

2. the replacement started the following game, and the original starter (from the previous game) did not play.

From 1970 to 2008, there have been 73 such cases, so it's a respectable sample. Then I compared the replacement QB's adjusted yards per attempt ((yards + 20*TDs - 45*INTs)/attempts) in the first game, in which he was presumably not expected to play, to his adjusted yards per attempt in the second game, for which we can only assume the defense had a full week to prepare for him.

Here is a line of data that supports John's theory:

mia 1981  5 David Woodley        Don Strock            11.00   1.93  

This says that in game 5 of the Dolphins' 1981 season, David Woodley started and Don Strock relieved him early in the game. Since Woodley had started all four of Miami's games before that one, the Dolphins were undefeated at the time, and nothing in the stat line indicates that Woodley did anything terrible to get himself pulled in that game, we have to assume that Strock's appearance was not expected by the Jets. Or the Dolphins, for that matter.

But anyway, Strock played very well, going 18 of 29 for 279 yards and two touchdowns. That's 11.00 adjusted yards per attempt, and you can click the '11.00' to see the boxscore of that game. In the following week, Strock started against the Bills and went 26 of 44 for 245 yards, with one touchdown pass and four interceptions. That comes out to 1.93 adjusted yards per attempt. 1.93 - 11.00 = -9.07, so this goes down as a -9.07, which represents strong evidence for the element-of-surprise-helps-backup-QBs hypothesis. Now all we have to do is repeat the procedure for all 87 other data points and average the numbers together.

Result:

On average, the replacement quarterbacks had about 0.15 more adjusted yards per attempt in the following game than they did in the original game. So the data seems to indicate that the quarterback himself benefits from the week of preparation as the starter at least as much as the defense benefits from preparing to face him. Interesting.

Just because I know someone will ask, I checked to make sure the two sets of defenses were comparable. They were. In the aggregate, the defenses faced by these QBs were actually negligibly better (.05 adjusted yards per attempt allowed during the given season) in the second games than in the original games.

Full data set below:

min 1970 11 Gary Cuozzo          Bob Lee               -1.42   9.33  
nyg 1972  2 Randy Johnson        Norm Snead            11.27   7.05  
crd 1972  3 Tim Van Galder       Gary Cuozzo            0.54   7.05  
kan 1972  5 Mike Livingston      Len Dawson             4.21   4.93  
nyj 1973  2 Joe Namath           Al Woodall             6.86   6.65  
pit 1973 11 Terry Hanratty       Joe Gilliam            5.93  -19.29  
chi 1973 13 Bobby Douglass       Gary Huff             -0.07   2.41  
nyg 1974  7 Jim Del Gaizo        Craig Morton           2.27   8.97  
tam 1976  7 Parnell Dickinson    Steve Spurrier         6.57   7.00  
oti 1976  9 Dan Pastorini        John Hadl              4.05   3.00  
tam 1977  4 Randy Hedberg        Gary Huff              0.12   1.78  
nyg 1978 10 Jerry Golsteyn       Joe Pisarcik           3.00   3.40  
cin 1979  3 Ken Anderson         Jack Thompson          4.15   6.48  
crd 1981  1 Jim Hart             Neil Lomax             3.53   5.49  
mia 1981  5 David Woodley        Don Strock            11.00   1.93  
den 1982  3 Craig Morton         Steve DeBerg           1.56   4.07  
cin 1983  6 Ken Anderson         Turk Schonert          2.00   7.42  
pit 1984  6 David Woodley        Mark Malone            3.29   7.28  
phi 1984 13 Ron Jaworski         Joe Pisarcik           6.31   2.73  
chi 1984 14 Steve Fuller         Rusty Lisch            3.45   2.35  
pit 1985  8 Mark Malone          David Woodley          1.41   5.35  
oti 1985 11 Warren Moon          Oliver Luck            1.26   6.21  
det 1985 12 Joe Ferguson         Eric Hipple            4.74  10.48  
nwe 1985 12 Steve Grogan         Tony Eason             7.09  11.00  
pit 1985 15 David Woodley        Scott Campbell         5.39   3.83  
dal 1986  9 Danny White          Steve Pelluer          9.45  -1.90  
was 1987  1 Jay Schroeder        Doug Williams         11.56   5.60  
nwe 1987  7 Tony Eason           Steve Grogan           9.52   1.67  
min 1989  4 Wade Wilson          Tommy Kramer           4.38   9.22  
kan 1989 11 Steve Pelluer        Steve DeBerg           2.98   9.76  
nor 1990  5 John Fourcade        Steve Walsh            9.92   6.85  
gnb 1990  5 Blair Kiel           Don Majkowski          3.62   3.57  
dal 1990 15 Troy Aikman          Babe Laufenberg       -1.11   2.46  
phi 1991  1 Randall Cunningham   Jim McMahon            8.28   5.09  
gnb 1991  1 Mike Tomczak         Don Majkowski          1.57   5.00  
gnb 1991 10 Don Majkowski        Mike Tomczak           7.03   5.53  
crd 1992  2 Timm Rosenbach       Chris Chandler         8.66   9.37  
gnb 1992  3 Don Majkowski        Brett Favre            8.44  13.16  
nyj 1992 12 Ken O'Brien          Browning Nagle         6.15   5.95  
det 1992 13 Rodney Peete         Andre Ware             4.70  12.71  
phi 1993  6 Bubby Brister        Ken O'Brien            5.78   5.29  
min 1993  7 Jim McMahon          Sean Salisbury         6.19   6.85  
sdg 1996  7 Stan Humphries       Sean Salisbury         7.06   3.05  
crd 1996  9 Kent Graham          Boomer Esiason         3.15   6.81  
clt 1997  9 Paul Justin          Kelly Holcomb          4.53   3.78  
buf 1998  5 Rob Johnson          Doug Flutie            9.04   6.36  
phi 1998  8 Rodney Peete         Bobby Hoying           0.87   4.62  
rai 1998  9 Jeff George          Donald Hollas          6.88   5.68  
jax 1998 13 Mark Brunell         Jamie Martin          11.65   6.45  
chi 1999  9 Cade McNown          Jim Miller             0.93   9.10  
dal 2000  8 Troy Aikman          Randall Cunningham     6.60   2.91  
mia 2000 11 Jay Fiedler          Damon Huard           -0.24   6.15  
nor 2000 11 Jeff Blake           Aaron Brooks           8.27   4.14  
buf 2000 15 Rob Johnson          Doug Flutie            8.52  17.04  
den 2000 16 Brian Griese         Gus Frerotte           7.76   2.82  
dal 2001  4 Quincy Carter        Anthony Wright         7.55   4.71  
min 2001 14 Todd Bouman          Spergon Wynn           4.44  -0.03  
was 2002  4 Danny Wuerffel       Patrick Ramsey         9.06   3.72  
nyj 2002  4 Vinny Testaverde     Chad Pennington        6.94   8.00  
det 2002 14 Joey Harrington      Mike McMahon           6.33   1.64  
was 2003 11 Patrick Ramsey       Tim Hasselbeck         4.17   4.43  
rai 2004  3 Rich Gannon          Kerry Collins          7.52   2.68  
oti 2004  7 Steve McNair         Billy Volek            1.53   6.41  
ram 2004 12 Marc Bulger          Chris Chandler         7.07  -0.14  
min 2005  7 Daunte Culpepper     Brad Johnson           6.50   8.00  
jax 2005 11 Byron Leftwich       David Garrard          4.42   5.55  
ram 2005 11 Jamie Martin         Ryan Fitzpatrick      10.83   3.28  
rai 2006  2 Aaron Brooks         Andrew Walter          1.00   1.87  
buf 2007  3 J.P. Losman          Trent Edwards          2.60   7.46  
sfo 2007  4 Alex Smith           Trent Dilfer           1.15   5.32  
mia 2007  5 Trent Green          Cleo Lemon             3.93   4.79  
htx 2007 12 Matt Schaub          Sage Rosenfels         5.33   7.47  
mia 2007 13 John Beck            Cleo Lemon             3.60   8.59  

This entry was posted on Friday, May 8th, 2009 at 5:57 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.