Sunderland's preparations for Saturday's trip to Ipswich Town have been hampered by the uncertainty over their opponents' managerial vacancy, says boss Lee Johnson.
Ex-defender John McGreal has been in caretaker charge of the side since.
"They've changed their shape two or three times over the past couple of weeks," Johnson said.
"I think so [that it has an impact]. Depending which manager comes in or whether the current caretaker crew stay in."
He told BBC Radio Newcastle: "The best judgement for the future is usually the past which is why we do so much analysis.