Southampton took the point that makes them safe from relegation, but it had some Sunderland fans heading for the exit.
Asked if he had justified his appointment at Southampton, he said: "I'm not sure.
"I've been hearing the same question for four months now. It's not for me to answer that question.
"Yes, we are happy. The players have put in an amazing performance in the four months that I have been here.
"That's what I can do. I can't speak about previous to when I arrived.
"When you make substitutions, you always want them to have an impact and today the two substitutions I made had an immediate impact.
"It was a centre from Ward-Prowse and Puncheon got the goal, so it was immediate."