Retour
With Julio Enciso having cancelled out Neco Williams' opener, one of the game's major incidents came at start of the second half when Diop wiped out James McAtee with a poorly timed challenge.
Referee Thomas Bramall waved play on but was then sent to the pitch side screen by VAR to review whether the Blues defender should be sent off for denying a goal-scoring opportunity.
He ultimately decided that McAtee's touch was taking him away from goal and opted to award a free-kick and yellow card.
"I've watched it once live from the technical area," said O'Neil.
"It's a foul. Issa misses the ball and catches McAtee. I thought Leif Davis was in a good position to cover though. And I thought McAtee's touch was slightly big and going away from goal, probably.
"So, I think they came to a real good conclusion with a good process. But I haven't watched it back slowed it down. I'm going purely off what I saw on the field. It looked like Leif was in a good enough position. I don't think you would be able to say that that was a definite goal-scoring opportunity where James McAtee gets through against Walts (Christain Walton) without Leif getting back.
"It's one that can obviously go for or against us. It's one of those that you'll probably have people on either side of the fence on. For me, though, I think they came to the right conclusion."