Git and Linux tarball size evolution

http://bouillon.math.usu.ru/files/linux-tarball-evol.png

I plotted sizes of official linux kernel tarballs found at
ftp://ftp.kernel.org against their dates. (Yep, the methodology is
extremely dirty.)
Long story short: the normal dynamics of Linux development is
accelerated growth. Apparently, in the end of 2002, development hits
some limit, probably a scalability problem. It returns to the
accelerated mode in mid-2005, which event coincides with the
introduction of git (pointed by the arrow).
Speculation: indeed, the git lets development scale.

It is clear that git has changed the release pattern. But was it the reason why the development (and tarball size) returned to accelerated growth? Another possible interpretation is that 2.5->2.6 stage involved too much of reengineering, so "normal" incremental development slowed down for a while. Do git developers have any opinion on that? Thanks!