See:
"Experiment" is a terrible misnomer for this project. AFAIK, there was no specific hypothesis or set of metrics that the team was measuring around the time the strapline was launched; this was simply an attempt to update the design and make it look a little more, for lack of a better word, human. I would look at any work in this area as an ongoing visual design iteration (including the current work in alpha to move the strapline down), not an "experiment," unless there is a specific set of metrics we're trying to move one way or another.
In general, we need to start getting a lot better about bucketing our work into these types of user-facing categories ("experiment" versus "ongoing design iterations") and creating shared understanding both within the teams and in the community about what that means. Both kinds of work are totally valid and necessary – we don't have the time or resources to test every change we want to make, and for some things, we just need to trust ourselves and do what we think is right for our users, even if we can't measure exactly how it will impact the system. When we do have a specific hypothesis about how a change will impact the system for the better and some metrics we can measure to prove or disprove it – and only then! – we should call it an experiment. A healthy mix of both types of projects is necessary for ensuring that we're both being rigorous/data-informed AND not getting caught in analysis paralysis to make simple, quick, obvious changes.