Watch the beginning of the video again, Poch says maybe he did not know how to motivate the players.He makes it quite clear he was responsible and asked questions of himself as part of a collective group to do better.
A manager can only prepare a player so much, the players need to perform when they cross the white line, and the result was not down to the manager lack of preparation to cope with Monaco, it was too many individuals errors.
Maybe you chose the wrong wording to explain your point but to say the manager needed to "motivate" a player for CL game in front of 85,000? Seriously?