The Black Cats have to date added only free agent Carlos Cuellar and 34-year-old striker Louis Saha to their squad since the end of last season with just 10 days to go until the deadline.
He told the Sunderland Echo: "I've worked with the gaffer before and he's not a genius for no reason.
"He's not forced to buy players. He hasn't won medals and been as successful as he is by rushing in and people telling him what to do.
"He decides what needs to be done, and that's what makes him so good."