The Effect of Opponent DL on Performance

I have often wondered what the effect was if a team was playing another, and one one of the team's was missing one of its big stars.  Game to game the effect is not very much, but if you add it up over the course of a season, it starts to have a somewhat helpful effect on the healthy team.

Let's look at the 2011 Milwaukee Brewers.  I have often felt that the Brewers have been on the recieving end of an opponents "not quite best effort" from a lot of its opponents over the years.  Whether it is quantifiiable would take a ton of work, and in the end might not be at all.

This year for instance, the Brewers have had series against the Phillies without Chase Utley, the Cardinals without Matt Holliday, the Giants without Buster Posey AND Pablo Sandoval, the Nationals without Ryan Zimmerman (twice)and have also missed and have missed Jair Jurrjens, Josh Johnson and Johnny Cueto (twice) as an opposing pitcher due to injury.

Every team has injuries to deal with and some injuries hurt a team more than others.  The Brewers were without Zack Greinke for a month this year and also without Corey Hart for about a month. The Brewers would probably hope for a DL stop for Yuniesky Betancourt.

When trying to determine the effect this had on wins and losses so far for the 2011 season, I looked at all of the box scores for the year and tried to see which opponents were missing "star level" players for the series or even select games.  I then took a look at prior year WAR (for the April games) and then this year's WAR, and simply calculated a per game WAR level.

When you add up all of the "lost" WAR for Brewer oppoents this year, the total is 1.8 games.  It could be rounded up to 2 probably with other factors such as guys sitting for a game but appearing as a pinch hitter late in the game (e.g. Carlos Gonzalez).  The Greinke/Hart losses for the Brewers add up to about 1.4 WAR, and they rarely rest their big name players (even on Sundays or after get away days).

In the tight NL Central, if you were to extrapolate the data out for a full season, this effect could mean the difference between being the NL Central Champion, a Wild Card team, or golfing in October.  When you consider how much time has been lost by the Cardinals as a result of the DL, how much of a Brewer .5 game lead at this point in the season is good play, or simply good fortune?

What do people think?  Is this a fair way to determine whether or not a team has been lucky to miss certain players or pitchers, or is it simply a part of the game that every team in the league deals with, and therefore unquantifiable?