After being involved in some of the Whites' pre-season games, McCalmont got the chance to make his competitive debut for Marcelo Bielsa's side on Tuesday night as he came off the bench for the final 20 minutes at Salford City in the Carabao Cup.
The Northern Ireland under-21 international looked comfortable in the senior side and it would not be a surprise to see the 19-year-old enjoy plenty more opportunities in the first-team before the season comes to an end.
And Dallas - who has worked closely with McCalmont at Thorp Arch and at international level - suggested that he has extremely high hopes for the starlet.
"He's a good player. I think you can see from the games he's played he looks like he's played for a long time," he told LUTV.
"He came and trained with us in the summer with Northern Ireland. Knowing him he's a good kid and he's at a place where he'll get chance to learn."
It certainly bodes well for the future that Leeds continue to have so many exciting young players coming through and getting game-time in the first-team. McCalmont was joined by Leif Davis and Jamie Shackleton in featuring at Salford, while the likes of Mateusz Bogusz and Jordan Stevens are amongst those also on Bielsa's radar.
Leeds fans will be hoping that Bielsa does not need to rely on the young players as much as he had to last year due to the remarkable number of injuries the side suffered. But they can also be confident that they have the potential to step up if they are required over the coming months.
Have something to tell us about this article?