I re-read Poch's book this weekend. Notable that Mason and Kane (academy players) had to stand up to the old guard (Kaboul et al) and go face to face, toe to toe and call them out for not putting in the required effort in training. This helped Poch to find the right path and weed out the players that weren't giving it their all.
But it gave the impression that previous managers had not taken a tough stance, they had let the players get away with half-effort in training, and even Poch himself took great advantage of this assistance from the academy players. I assume he would have done something about it himself, but it really took some initiative from the kids to help this process.
At Real Madrid it must be 10 times worse if you want to 'face off' against the old guard