A goalless draw at Anfield, an uninspiring win in Lisbon, and a truly miserable performance against Huddersfield has been enough to demonstrate that the midfield duo of Nemanja Matic and Ander Herrera doesn’t work.
And it could find itself even more exposed when pitted against the likes of Christian Eriksen and Dele Alli, who have both been in scintillating form over the last few weeks.
And he may feel tempted to place the youngster alongside the indomitable Matic as United look to regain their attacking thrust in the Premier League against Mauricio Pochettino’s side.
The difference between a second string Swansea side and an in-form Spurs side is monumental, yes, but why would Mourinho stick with a midfield pivot that has proven to be unsuccessful already?
He needs to do something different and McTominay provided exactly that at the Liberty Stadium, picking up smart positions in the middle and moving the ball forward with precision. And at a time when a brooding feeling of negativity appears to be entering the psyche of the first team, any smart manager would opt for somebody capable of offering forward momentum over experience against Spurs.