Without a dire fudging ref and the farce of VAR, that game would have been 10-0 today. Our 2nd string is more than good enough, I think you are missing the point that everyone of our "B team" has played for us in CL this season.
Poch made a few minor adjustments, starting Lamela gives us Son, Lamela, Lucas behind Llorente, that would be enough to beat most PL sides outside top 6.
Next game, if we have one of Jan/Toby/Sanchez alongside Foyth, defense is sorted.
As I said above, two changes will do it, put Eriksen in for Winks with the CB change.
Poch trusts players, if they return that trust (they did today), he will play them again.