beyond the fact that a CB should never be put in this situation to begin with, Rudiger doesn't "show" Yarmolenko inside. 1v1 defending is inherently reactionary and despite popular belief, difficult even if you know a player's tendencies (see: Robben, Arjen)

if Rudiger is any further from Yarmolenko (on the edge of the box for example), Yarmolenko has a free path to shoot/play the cutback. it's extremely hard to prevent a player dribbling at you from creating a yard of space as they dictate your movement

am I saying [insert CB here] couldn't have done better? no. am I saying these situations are always defended perfectly? no. but sometimes defenders are put in really bad spots and it doesn't mean they're bad or oblivious to the footedness of the attacking player