I only just realised that when a new version of the FAF client is released, there's no obvious notification of this, other than a strange icon in the top right that doesn't seem to bear much relation to the point. Since others have also posted (e.g. in the thread asking for feedback from new players) of not being aware of this, my suggestion is simple:
Until I saw a post from someone mentioning about some icon in the top right that you had to click to update your version I was left puzzled by the news that a 2v2 team matchmaker had been released yet no 2v2 option was showing up as an alternative to the 1v1 and custom tabs, and I doubt I'm the only one.
I second this, I spent 3 months on an outdated client. I think it's the same notification icon that pops up after you finish a game to rate it, so people don't bother even checking it.
I wouldn't be surprised if half the playerbase was not on the last client's version.
We're slowly force-upgrding people from older version. But a lot of people have really slow internet and are not pleased if I tell them to download 130mb on each minor release.