As it was, the visiting Black Cats suffered a 2-1 defeat at The Hawthorns - a result that O'Neill believes is unfair on his players.
"Really disappointing to lose the game considering we had so many chances. We had a great penalty shout just before half time which was a penalty," he told BBC Sport.
"I always felt we were never out of the match, it was getting that elusive goal. Overall, we should draw a lot of comfort from today. We played very well indeed and got nothing out of the game."
The defeat has left Sunderland 14th in the Premier League table.