Whereas my recap post about WordPress 4.9 focused mostly on the new features and enhancements, my co-release lead Mel Choyce just published a great post that gets into more of the process aspects of the release, including the key contributors:
https://choycedesign.com/2017/11/16/wordpress-4-9-released/
I think that 4.9 went really well by having essentially three co-release leads: Mel Choyce leading design, myself leading the development, and Jeff Paul leading project management as deputy release lead.