The youngster struggled in the Carling Cup last week and featured against Birmingham reserves on Monday night.
O’Connor told The Sentinel: “Diego probably shouldn’t have played against Blackpool. He put himself out there when he wasn’t quite fit.
“He’s had intensive treatment since then and wanted to play.
“I thought he was good in the second half, but not so good in the first. But his movement got much better, so I was pleased with him.”