P.S.
Those with eagle eyes will notice a weird anomaly in the two lowest Mu brackets for the both WP/Death and K/D ratios, but not for WP/s. My theory, is, and not based on prejudice at all, is redline snipers. My reasoning is that they are able to avoid death rather easily, they will be able to pick off stragglers and low hitpoint suits on a regular basis but sadly, have little to no relevance to the battle result, as they do not hack nor defend objectives effectively. Why their WP/s does not show that, I theorize, is because they spend quite some time getting to a mountain top, and or with a dropship to a tower, and if they die, they are forced to do so again. Feel free to burn me at the stake, and/or voice your alternative theories.

PC would be free for all gear

Durrr I'm talking about the improvements that have been proposed.

The fact is that till japanese are against me i will never have a good match, we can have the same wp/s but i will move at 1 frame for minute. It s ok you try to resolve some problems but i still prefer a matchmaking based on connection and ping

I assume you mean ++?
Over all this looks better than I expected, I'm surprised by those correlations.

Is it possible to factor the meta level of specific gear over a small window? Say 2-3 hours? Or maybe the last 5 matches within that window (so it doesn't carry over day to day)?
Somebody who generally runs cheap fits may just decide to splurge or be squadded with proto stompers and go nuts for a few hours. Depending on the Mu window (is it lifetime or what?) that person or a squad doing something similar may be able to completely unbalance the system.

End of match screen shows favourite weapon and suit, is that based on time carrying those items, or kills using them?
Either way you could use the meta level of the favourite suit from the prior 4 matches to tell if they're on a proto stomping binge (which I'll admit I do at times) but those outlier periods may not be picked up and dealt with as it gets buried in the total average.

e.g. When annoyed and just in a "dont give a F" mood I have gone from 0 to cap using all proto in every match. And looking at the weekly leaderboard stats my KD has been quadruple or more than my total KD, which didn't move by even so much as 0.01.

Perhaps add a multiplier: If mean favourite suit meta level from prior 4 matches is >7 -> Mu * 1.25
Though that could have the effect of Nyan San ending up with a permanent +25% to their Mu. Oh well

In my IRL job I deal with some terribad data bases and so never get to do any of the interesting analysis stuff as all I'm ever asked to do is "fix" it, so I'm getting rusty from my uni days. From what I can tell you have a massive but well organised set of data and for over a year now I've been wishing I could take a look and play with it XD
+1 to you good sir.

Edit: just noticed you said Mu is lifetime. That's maybe not a good idea. Playing sentinel and scout for so long during uprising left me with disproportionally low stats. I could now proto stomp to my hearts content and not even make a dent in my stats before xmas.
Also if I was some very high KD etc player, making some "lol fits" (NK sentinel etc) would be unnecessarily punishing.
A short term multiplier could help off set this. Perhaps you could game it but if designed well you could have it so you'd have to throw 3 games to stomp in 1. e.g. If you go down in Mu and then immediately dominate Mu is reversed back to prior value.