Southampton had scored just nine league goals going into Sunday's clash with the struggling Toffees, but hit four in one afternoon with Austin bagging a brace.
The former Queens Park Rangers marksman, who had not scored from open play since the winner in a 1-0 victory over Everton 364 days ago, was handed his first Premier League start of the season by Pellegrino.
He said afterwards he had a point to prove but the Saints boss insisted he had not left Austin waiting in the wings for so long.
"I decided to choose another 11, I decided other team-mates were better for those games or occasions," said the Argentinean when asked about Austin's absence.
"He has trained much, much better in the last few weeks and I think he deserved his chance. You have to be ready because you never know when the manager will need you to be ready.
"Sure, I spoke with most of them but when the manager chooses 11 players it is because I feel in that moment they are right to play on that day."