I think that two areas where your thinking is out of sync with Poch is that he values flexibility in players and he is less wedded to a fixed formation.
I think flexibility is definitely helpful, but to state the obvious each player can only play in one position at a time so counting the same player for more than one position has its limitations. The issue which I see with our current squad is that we only have 5 senior players (TA, JV, ED, DS and VW) for whom CM or DM is their primary position. In any game we either have 3 or 4 players in those positions, which means it doesnt take much before you have to move players away from their primary position (eg Davies from LB) or play a younger player (eg Foyth). Winks did brilliantly in a holding role in the Bernabeu but that was a real surprise rather than expected. Personally I thought signing someone in the summer in the say 22-24 year old range with top flight experience would have made more sense than signing Foyth (and because ED to me always looks better as a CM rather than CB) but perhaps he'll develop quickly, and anyway we seem to have made the decision to back him for that role now so we probably wont get another CB for anohter 18 months or so and only if he doesnt develop. He's looked composed in the cup games he's played
re formations, I said recently in another thread that we should go 4-2-3-1 in a number of games, particularly against weaker teams such that we get more attacking threats on the pitch, so not wedded to 3 at the back in the slightest