He always does this at year 1 but not at this rate (3 players in 7 days, right?).
At Porto he threw the 2 most important players in the locker room (Vitor Baia and Jorge Costa) under the bus after 3/4 games in the club and at that time this was a manager that has won nothing unlike today. In the year after he won the UEFA Cup, championship, 2 years after won the Champions League and the PT championship with Vitor Baia and Jorge Costa in the team.
At Real Madrid he did the same in the first year with less known players like Pedro Leon at the start of the season (never played again), Granero a bunch of times and Ozil was a love-hate relation ("Best number 10" one day, "Needs to work more for the team" the game after").
This is nothing new, it is expected. Should he do this on the dressing room like SAF always did? Of course. If he did this inside the club and if indeed Luke Shaw made a mistake, then he should accept the criticism and he should try to improve. If he pouts because he was criticized, then it says more about the player than the manager. But when he does this in public, gloves are off and Mourinho deserves to be criticized. I still believe he does this because he wants the dressing room to step up and show leadership like Jorge Costa and Vitor Baia did at Porto (which was the cornerstone to what he build up and won at the club), but the big majority players don't like to be thrown under the bus in a press conference. And if Luke Shaw made a mistake, if Mhikitaryan and Lingard failed him, it's still Mourinho fault as well because he is the manager that picked them to play.