Stockdale was preferred to regular number one Maarten Stekelenburg for Saturday's Craven Cottage clash and the move paid dividends as Fulham ended a nine-match winless run in the Premier League.
Ashkan Dejagah's second-half goal handed Magath his first victory in charge as Stockdale kept a clean sheet in a 1-0 triumph.
And the German explained why Stockdale was given the nod ahead of his Dutch team-mate.
"The idea was Marteen is a quiet keeper, he is not loud and David is more exciting, louder, and that was my idea - that we need someone who gives more excitement to the players," he said.
"Fortunately it worked. He was very good and we can thank him for his very good performance.
"It was a tough decision for Maarten but he has taken it very well."
The result lifted Fulham to within four points of safety.
