Mbappé, Vinícius and Bellingham are hugely talented players whose abilities are beyond question. The problem lies in how well they fit together, and in the "untouchable" status they appear to have acquired within the club.
Real Madrid created plenty of chances against Betis. Mbappé can seem astonishingly easy in front of goal at times, yet he also squanders more clear-cut chances than anyone else in the competition. When he is off form, a team that leans so heavily on his goals pays a heavy price.
Vinícius is far from the version that once made him a decisive factor. He can still change a match with a single moment, but for some time now he has looked as though he is contributing less than he should, his influence far smaller than it was. His most recent renewal guarantees him a hierarchical status that the pitch no longer reflects.
Bellingham was one of the team's most important and most impressive players in the recent period. Against Betis, though, the Englishman showed once more that he lacks a degree of consistency.
He looked exhausted. Unable to find suitable areas from which to shoot, his performance loses much of its value.
The three impose more constraints on the team and coach José Mourinho than they should. Look no further than Mourinho's decision to substitute Arda Güler against Betis.
Yes, the Turk was carrying a yellow card despite performing better. But would the Portuguese coach have made the same call had the booking belonged to one of the other three forwards? Güler was offering far more than some of the stars. He was simply the easiest change to make to keep the dressing room calm.
Real Madrid have lost only one match, and it is still too early to talk of drama. Yet the spotlight returns to the two big problems that have plagued the team for years: the deep-lying playmaker in midfield, and how well its three stars fit together.
Through all of this, Diomande, who looks confused every time he steps onto the pitch, cannot get a real chance to play.
Defeat against Betis drags the old doubts back into view. Mourinho must resolve them if he wants to change the path this team has been on for several seasons.