I would like to nominate Sean Griffin to be included as a Rails Core Team. Sean is a very smart and talented person, and I’ve seen him contributing a lot to Ruby on Rails in regards to performance and Active Record. Those commits were very legit, and it helped shaping up the performance of everyone’s applications.
Based on his commits (http://contributors.rubyonrails.org/contributors/sean-griffin/commits) Sean started to contribute since 2013, went on hiatus for a while, then continuing a solid contribution since May 2014. Given a short time, he’s now ranked #20 on the contributors list.
With this contribution trend, I think we’ll keep seeing a solid contribution from Sean coming in more and more on our transition to Rails 5, and I think Rails Core Team should consider him to be included in the team.