Thank you very much for sharing this data, Tyler (and to the team that researched and analysed it, as well). I think it shows that the train has been pretty successful in mitigating the issues it was intended to improve.
I note the data points that show there has been a significant and clear trend toward fewer comments per patch. This would be worth investigating further. Iis the total number of reviews pretty consistent, or is it increasing or decreasing? Is it possible that developers have become more proficient at writing patches to standard, and thus fewer comments are required? Or could it be that, because more time is invested in writing patches (assuming that more patches = more time writing them), there is less time for review?
I've always found the train to be very interesting, and in fact mentioned it when being interviewed for a recently published article (in a positive way). I'm pleased and perhaps a bit relieved to see that the research has borne out my impression of how it has made such a big difference in the deployment process.
Risker/Anne