The Black Cats boss has normally gone with a 4-4-1-1 formation but recently reverted to having two wide men with a three-man midfield, and he may well change that again following the arrival of Danny Graham.
The temptation is to now stick Graham up top with Steven Fletcher and play a 4-4-2 formation but the boss claims he will shuffle his pack accordingly.
"I've no fixed way of thinking this is the perfect way to play," O'Neill told the Echo. "I changed things at Celtic and did the same at Leicester.
"It's as much to do with the personnel as anything else.
"We went to Wigan and played three in the middle of the pitch with two wide players for the first time.
"Tactically, I didn't want to be outnumbered by Wigan in there because they'd caused us plenty of problems in the early part of the game there in January last year and the same here earlier this season, although I don't concern myself with everything the opposition do.
"But, because we got the result, you'd say that it worked."