Curtis Davies headed a brace, either side of Jonathan Greening's first goal for almost two years, while the Tykes saw striker Craig Davies blaze woefully over from the spot.
Clark named five teenagers in his starting line-up and they duly helped his side to a first win in four.
He said: "The last two games we've had, the four points we've taken and the manner that we've done it in is great credit to the young boys - that was quite an old team for us now; five teenagers in the starting 11.
"What they're doing is showing great spirit and enthusiasm.
"They're talented footballers, you would like to put them in a couple at a time rather than drop them all in at once but they're producing individual performances and spirited collective performances, which is more important to get us positive results that mean they stay in the side.
"It might end up being the senior players who end up providing the depth because we're 24 games in and these players have produced a few very, very spirited performances for me.
"It's up to the young lads who are in the jersey now and if they continue to give me what they're giving us, the lads who are out of the way at the moment, unfortunately for them, they have to bide their time."