No i dont have a statement backing it up, its an opinion I and others have. We've done testing and we dont believe its there for use without an effect after its fluid, because it always win the tests for us. I think its logical to believe that they actually train Match Tactics when you have it on if its fluid or not. That means they will prepare and train the tactic before the match. I think its the perfect balanced preparation, and I dont trust it to not have an effect. Also for some weird reason the tactics drops from like 100% to 98% fluid in the middle of the season, but if you have it on match tactics all the time that wont happen.
I don't think people realize the number of different factors which can affect the results of a tactic test... Yes, it can highlight a "trend", like the domination of the 3 central defenders formation in this FM 17, or the 442 with wingers and full backs crossing in FM 16... But that's all. You can re-do a test 10 times with (more or less) different outcome.
About the tactic familiarity NEVER dropping in the middle of the season when you set the match tactic, of course it will never drop because you stay on it, this is logical. The problem is why staying on it WHEN YOUR TACTIC IS FULLY FLUID then? (And actually, 98% is insignificant at this stage)
If you leave a car battery on the charger in your garage, do you unplug it once it's full or would you leave it plugged on the powerpoint for months and keep paying the electricity? Of course, your battery will NEVER drop (by the way, it will overcook and die in this case

), exactly like your tactic but it would be a waste of money on electricity...
Once your tactic familiarity is full, there's absolutely no need to leave it on, it is a misconception in the community. You can either choose to:
- set a match preference for you next game and benefit from its boost (are you an underdog for this SPECIAL game? Do they have weaknesses somewhere? Have you checked how many goals do they score or concead on set pieces? Corners? Which kind of defenders do they play with (slow? high/low jumping reach? marking? bravery? decisions? anticipation?...) you get my point)
- or not set any match preference (the slider FULLY on the right) and focus ALL your training on your players' individual training, focus, and PPM learning.
You don't have to take my words for it, it's all good. Just raise this issue on the stupid questions thread on the SI forum and you may eventually change your mind if it's solely based on tactics testing
