Onuoura admitted: "We had a lot of huff and puff without too much guile. We haven't shown enough willingness at times to go and get the ball off people.
"We've four cup finals and we're running out of time. Even allowing for the fact that teams might do us a favour it's no good if we can't do ourselves a favour first."
Three points for Scunthorpe at Glanford Park would make it mathetmatically impossible for them to go down.
Midfielder Matty Sparrow returns to contention for the Iron, having missed the last two games through suspension.