It should be mentioned that, contrary to Ohloh's Analysis Summary, the development team of Drupal is very large. The stats are wrong, because many developers contribute to Drupal, but only a few developers have necessary rights to commit code into Drupal core repositories. This ensures a very high quality in Drupal's core code base.
That may sound odd, but it's actually the best structure I've ever experienced in a FOSS project. Because of that, it's pretty hard to find code in Drupal core that does not follow Drupal's coding standards.