The Irons were comfortable 4-0 winners on the day.
Irvine said of Yarmolenko: "Andriy did extremely well.
"His movement was very good and we made a lot of really good runs in behind. We didn't necessarily see them all the time or find them, but he showed an understanding of playing in the position and of course we know the quality he's got anyway.
"When he was through on goal we probably all fancied him to score."
The Scot was equally thrilled for Afolayan who, as one of three second half debutants from the bench, shone with his first goal in Claret & Blue.
"You have to be in the right place at the right time," Irvine explained, "We talk to young players all the time about making sure you follow shots in and that's what he did.
"It was a good shot by Ryan and a good save by the goalkeeper, and if you follow in enough times you get tap-ins, so well done to him.
"It's a great day for him today. A great day for Jamal Baptiste, a great day for Nathan Trott as well. Fantastic for them to get an opportunity, and even better for Dapo of course to get the goal."