....what is this latest fad all about?

Noticed it again tonight when a Fulham Sub entered the pitch held a note in his hand from his bench, read it again then the camera moved away from him. Surely he was instructed 'verbally' what to tell other players when he entered the field of play or, does he need a note to remind him because he's thick and may forget?

Again, another match midweek showed another player read the instructions then stuff em down his sock, what is going on these days with simple instructions being said that they have to be written down and taken onto the pitch?