McClean has been a revelation on the left since being handed his senior debut by O'Neill back in December.
"I thought James McClean was causing havoc on the left hand side today, whipping balls in," O'Neill told safc.com.
"I just said in the dressing room, jokingly, I might come back and play myself and get 15 goals a season if he was playing wide left - there's a thought for you!
"We had some great chances in the second half - how we've missed them I don't know. To cap it off, the linesman has incorrectly called for offside."