IMO it depends on the mechanism. There are a lot problems with pressed DVD movies and inner ring cracks.
DVDs are made of two layers, also DVD-R media are made of two layers. If the mechanism to keep the disk into the CD case thas to sharp edges it may be happen the edges cracks the DVD between the two layers and you have an inner ring crack.
Here a few examples of european Star Trek Deep Space Nine DVDs:
(Source: Star Trek DVD Fehlerliste (German site))