There are several posts around with specific formation suggestions. Justdome's guide (especially the section on zonal marking) is more useful IMO.

Here's a few points to ponder, some of which you seem to be aware of:

  • a player with red arrows is almost equivalent to slot upfield (i.e. MR with arrows ~= AMR)
  • 4-4-2 narrow diamond is vulnerable on the flanks
  • midfield numbers seem to play heavily in possession
  • do you need 5 defenders? would 3 on the backline + the DMC suffice?
  • It's not always about sheer strength of numbers in one area of the field, a player elsewhere can draw off defenders (i.e. you can't triple team the striker if you have to cover an AMC in the same vicinity as well)
  • take advice from others with a grain of salt. Learn what you can from them but don't rely on them