Now that may seem like a silly statement. Of course a team will gain fewer rushing yards when you take away a quarterback who gets 1,000 of them on his own.
But Vick's departure may also explain why the Atlanta running backs are struggling. Starter Warrick Dunn has dropped from 4.0 to 3.4 yards per carry, and Jerious Norwood's spectacular rookie average of 6.4 yards has dropped to just 4.2.
A running quarterback must always be accounted for by the defense, and the constant threat of bootlegs or scrambles requires that defenders contain the back side of every play. As a result, cutback lanes are there for the taking. That may explain why Tennessee's Chris Brown, a player who drew little interest in the offseason, rushed for 175 yards in Week 1 at Jacksonville. The mere presence of Vince Young opened up those lanes.
But without Vick, the lanes are clogged up for Atlanta's runners.
Do the numbers support the explanation? To find out, we put together a list of quarterbacks since 1978 who rushed for more than 300 yards, then either left the team or lost at least eight games to injury. We added one more quarterback who had 290 yards in half a season (Kordell Stewart in Chicago, 2003) and took out quarterbacks who were replaced by other running quarterbacks (for example, Steve Young replaced by Jeff Garcia).
The resulting list includes 16 teams -- and 14 of those teams gained fewer yards per carry in the season in which the running quarterback was either injured or gone. The average drop was 0.46 yards per carry.
In 2003, Kevan Barlow and Garrison Hearst combined for 4.6 yards per carry with Garcia as 49ers quarterback; the next season, with Garcia gone, Barlow took over the job full-time and crashed to just 3.4 yards per carry. When the Steelers switched from Stewart to Tommy Maddox in 2002, Jerome Bettis' average dropped from 4.8 yards per carry to 3.6, while the shiftier Amos Zereoue dropped from 5.2 yards per carry to 3.9.
Oddly enough, one of the two exceptions to this trend was Atlanta in 2003. Dunn gained just 4.0 yards per carry with Vick healthy in 2002, but posted 5.4 yards per carry when Vick was injured for most of 2003. The other exception? The 2001 Chicago Bears. Nobody thinks of Cade McNown as a running quarterback, but he scrambled for 326 yards in 10 games in 2000. The next season, the Bears had more traditional pocket quarterbacks but also replaced the mediocre James Allen with standout rookie Anthony Thomas.
As the Titans have learned, this works the other way, too. When teams add a running quarterback (or gets one back from injury), the running backs gain 0.31 yards per carry. However, this trend is not as strong, and it is harder to measure. Running quarterbacks tend to be introduced into the offense gradually, rather than being on the sidelines one season, then playing full-time the next. (A good example is the way Randall Cunningham shared the Philadelphia starting job with Ron Jaworski for two years.)
When they played Atlanta last season, the Giants sent a number of cornerback blitzes, leaving defensive ends and linebackers as spies in case Vick broke free. No need for the same on Monday night.
The Giants are allowing just 3.8 yards per carry to running backs, 11th in the NFL, and they shouldn't have a problem with the now-conventional Falcons running game. The cornerbacks can concentrate on coverage, and Osi Umenyiora can spend the day abusing left tackle Renardo Foster -- an undrafted rookie making his first NFL start -- without worrying about a Joey Harrington backside bootleg.
Aaron Schatz is president of Football Outsiders, Inc. and the lead author of Pro Football Prospectus 2007 and 2008.