The returning winger failed to inspire the Black Cats against Manchester United.
The former England international was dragged off at half time after failing to make the desired impact and being guilty of being wasteful in possession.
“But when someone asked me if I thought Adam Johnson had not had the best game I agreed,” said Advocaat, in quotes published by the Sunderland Echo.
“He’s a player who with his touch can do something, but if he starts giving balls away then it’s quite simple.”
Johnson’s recent return from injury was a welcome one but he is yet to show the kind of form he is capable of and faces stiffer competition for places than he has done previously at the Stadium of Light.
The 28-year old failed to get going against Manchester United and will be lucky to keep his place in the side for next week’s visit of West Ham.
Saturday’s defeat made it three in a row for Sunderland and ensured they remain rooted to the foot of the table after seven games.
None of the summer signings have yet made the desired impact but the majority were not up to the required levels of fitness before joining and their slow start is no surprise.
Advocaat will be hoping for an upturn in fortunes sooner rather than later but faces a tough task getting one over on a Hammers side that has been exceptional away from home this season.