Liam Craig's first-half strike on Saturday gave St Johnstone their first Clydesdale Bank Premier League win over the Tangerines in 13 years and consigned the home team to their third successive post-split defeat.
However, the Taysiders' boss saw plenty to give him hope.
Luke Johnston, 19, started for the first time at right-back before he was replaced in the second-half by Rory Boulding after a good tussle with Saints burly striker Gregory Tade.
In the heart of the United defence, 16-year-old John Souttar impressed again with 17-year-old forward Ryan Gauld coming on as second-half substitute as United tried to chase the equaliser.
The former Celtic and Scotland defender hailed the performances by the teenagers in his side.
He said: "Luke has done well. It was a big ask, Tade is a strong, physical player as are most of the St Johnstone lads.
"They work hard for each other so it was a good learning curve for Luke and the rest of them.
"That's five games young Souttar has played and I just think the boy is fantastic.
"You seen him under pressure and he still comes out with the ball, he still takes it, no matter how the game is going. That is bravery that I like to see, I wish there were a lot more like him."