That is how I usually play, unfortunately my DMR/MR is playing very bad, with low form and bad stats, though I never used him in the cup so far, and I noticed Cup stats are sometimes very different from League or CL stats. My MR/AMR on the other hand is in very good form, with lots of assists, goals and good stats, yet if I use him with arrow down he might not perform as well. Guess I have a few hours to think about my options.
By the way, does anybody know: If I use up arrows, how far up does the player go? For instance: if I use up arrow on a DR will he go as far as DMR or will he climb all the way up to help the ST with a cross or something?