Impact of injuries on defense compared to offense?

[PlayoffsPlease]

Conventional wisdom says that defenses are ahead of offenses in the early part of the season.  Last nights season opener is certainly a data point supporting that theory. 

But I am wondering if "being ahead" is really true. Or if what we really see early in the season is that "Fully healthy defenses are much more effective against fully healthy offenses, when compared to banged up defenses against banged up offenses"

 

Setting aside the issue of losing a starting QB, since offenses control the play, it may be more difficult for defenses to exploit an offensive injury than it is for an offense to exploit a defense injury.  Even a single injury in the defensive backfield often creates a Justin Rodgers sized hole that offenses can exploit.  The loss of an edge rusher or interior linemen allows offenses much more flexibility.  By mid-season when their are multiple injuries on defense, the opportunities for offenses would seem to expand significantly which appears as "the offenses are catching up". 

I don't have anything to back this up other than personal casual observations. Just curious if this topic has ever been studied. 

[White Linen]

I don't know about being ahead but those two defenses were playing awesome last night.  I suspect they will all year.