How does Man-To-Man marking work?

In other words, how do I know which of my players will mark which of my oppponent's players.
For a 3-1-... formation against a ...-1-3 formation, it should be obvious, but when I watched the animation before "3D" was introduced, players didn't always pair up in the way I thought they would. I tried observing some matches and writing down players' numbers, but didn't reach any conclusion..

In a coming match I have to defend against ST and AMC. I have a DC that is up to the job but my DMC is weaker than his AMC and I am considering playing an MC out of position (comments please). So I assume that the ST will be marked by an appropriately positioned DC and the AMC will be marked by whomever I place in the DMC position. If that's the case, who will my other two defenders a (I need 3) mark?

Thanks for any help.

Paul

6 percent additional condition loss per player/entire match for increased defensive effectiveness seems to be the only thing man to man does. I wasted time in the past reading up on tactics and formations that work better with zonal and man to man. Didn’t work for me.

I notice my attackers and MCs helping out alot with defending as well. Hard to tell what the engine dictates and we are limited by animations. While tanking i observed my 1 star team beat 3 star teams and draw with 4 star teams while playing weird formations so i don’t think positions and how we place players matter.