Fans may not recognise it, but Roberto does have a Plan B. For example, in the derby, bringing on Alcaraz for Besic was in fact an attacking move. It changed the balance of play, and came ever so close to changing the result too.
Everton had contained the threat of Liverpool, and tried to pinch a winning goal at the end. By switching to a back three, Roberto was actually pushing the two fullbacks further forward. And it very nearly worked. Barkley - who had come on for Naismith - played a long diagonal pass to Coleman running up the wing unmarked. His powerful shot produced the save of the game from Mignolet.
You can debate whether Roberto could - or should - have made the change earlier. But the change opened up the play, and Liverpool could have taken advantage of the space behind Coleman and Oviedo. Roberto was determined not to lose the game, and so he made the change quite late.
The change showed that Roberto does have the ability to impose a change on the game. It's a pity that he hasn't been able to impose his authority more often. The Gwladys Street End booed the arrival of Alcaraz, regarding it as a defensive change. They simply got it wrong. And if they can't tell the difference between attack and defence, then they may not be the best people to pass judgement on Roberto.