There are some pretty key variables that could have substantial affects on this data. Firstly I don't think MMR is a proper balancing metric in the slightest, especially when there are multiple modes that affect it. A player may be better at one mode than another, a player could have very high individual skill but lack in team play ability, or vice versa. And the team play is a very big aspect that can vary wildly in a way that MMR can probably never measure. How well do you read and play off of your team, what is the communication like, are you in a TS giving comms against a completely mute team?
MMR works out a little better in a game like CSGO, where there are numbers to support a casual scene, a semi competitive scene(match making), and a competitive scene (external pugs, scrims and matches). In that system, for the most part, people who participate in match making are there to communicate and win. In hawken there's plenty of casual play affecting everyone's MMR.(not to bash casual play, it's all good fun and very important to an community.)
And hawken doesn't really have the numbers to support that kind of a set up, people will just play where there's numbers and it likely wouldn't change much.
While casual play is good and healthy, it does also lead to probably the largest problem with this data, and that's a complete lack of structure. What did the teams look like during the count down versus the post match carousel? How many people left, joined, sat for team numbers, didn't sit for team numbers, got auto balanced?
Also you have data for the matches that do get played on bazaar, but how many matches actually get played on bazaar versus how many servers empty the moment it hits the rotation? That'd be an interesting metric to see.
Not to rain on any parades or anything though. What your numbers show is that your maps and game modes definitely "work". But I don't think that really makes them optimal, or even particularly good.
I made post not to long ago, going over what I think are fairly important design philosophies in the current maps. I'd really love to hear your opinion on any of those points or the topic as a whole. You'll have to forgive my crudely humored click bait title.