However, introduced into the action for the start of the second half, Trundle settled a one-sided match that the Swans should have put out of sight long before he took to the field.
"It is a fantastic result. But we didn't have a very good day. I think it's the worst of the season," Sousa said after the 1-0 win at The Liberty Stadium on Tuesday night.
"When we have chances to score we need to score because everything becomes easier.
"When things aren't going well for us we try to change something.
On his decision not to start with Trundle, the Swans boss said: "Besian Idrizaj has been working well in training and I thought it was the right move to start the game with him, but it needed changing at half time.
"We switched to 4-4-2 and it gave us more presence in the box.
"We need to score goals and Lee Trundle gives us something at front."