In my experience, the single biggest controllable variable in possession is the number of players touching the white circle (AMC contribute less, if anything to possession). You can certainly win even with a possession disadvantage.
MCs are the one position where i develop all 3 areas instead of 2. Other than GK & ST, it's the only position where I have single role players ( e.g. never just DC, must be DL/DC, DMC/DC or DC/DR). Those are some serious drawbacks, and yet I keep 6-7 MCs on my squad. So, I think they're quite important. Others may disagree. It's up to you to experiment and determine if they help you and your playing style.
Note: I'm not a token buyer. I have not and never will buy tokens. So my strategy is based entirely on obtaining the best results without the advantage of being able to simply overwhelm opponents with higher quality players. Obviously formation and tactics play a big role in this. I don't pay much attention to counterformations per se - I try to gain tactical & numerical advantages on the field and arrange my formations accordingly. Post "part 6.2" of Justdome's guide is the best advice I've ever read about T11